Fatty Acids Overview
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Questions and Answers

What is the primary characteristic of leukotrienes?

  • They contain multiple hydroxyl groups and are saturated.
  • They are exclusively produced by COX-1 enzymes.
  • They are c20-fatty-acid derivatives with three conjugated double bonds. (correct)
  • They contain no double bonds and are not associated with inflammation.

    • What is the role of nonsteroidal anti-inflammatory drugs (NSAIDs) in relation to COX enzymes?

  • They inhibit COX enzymes to increase eicosanoid production.
  • They enhance the activity of COX-2 enzymes.
  • They specifically target only the COX-1 enzyme without affecting COX-2.
  • They inhibit COX enzymes, which reduces eicosanoid production. (correct)

    • What distinguishes COX-2 inhibitors from traditional NSAIDs?

  • They have no effect on inflammation.
  • They selectively inhibit COX-2 to reduce inflammation with fewer side effects. (correct)
  • They increase the production of inflammatory eicosanoids.
  • They inhibit both COX-1 and COX-2 mechanisms equally.

    • What type of fatty acid are leukotrienes derived from?

    <p>c20-fatty-acids.</p> Signup and view all the answers

    Which of the following is NOT a known effect of leukotrienes?

    <p>Induction of reducing inflammation.</p> Signup and view all the answers

    What type of fatty acids has more than one carbon-carbon double bond?

    <p>Polyunsaturated fatty acids</p> Signup and view all the answers

    Which statement accurately describes trans fatty acids?

    <p>They are a minor product of animal and plant metabolism.</p> Signup and view all the answers

    Which of the following fatty acids is also known as linoleic acid?

    <p>cis-9-, cis-12-octadecadienoic acid</p> Signup and view all the answers

    What effect do cis double bonds have on the melting point of fatty acids?

    <p>Lower the melting point</p> Signup and view all the answers

    Which statement is true regarding the solubility of fatty acids?

    <p>Longer chains are less soluble than shorter chains.</p> Signup and view all the answers

    Which of the following fatty acids is associated with brain tissue?

    <p>Arachidonic acid</p> Signup and view all the answers

    How does increasing the chain length of fatty acids affect their melting point?

    <p>The melting point increases with longer chains.</p> Signup and view all the answers

    What is the primary reason for partial hydrogenation of fats and oils?

    <p>To increase melting point and improve stability</p> Signup and view all the answers

    What type of fatty acids are solid at room temperature?

    <p>Saturated fatty acids</p> Signup and view all the answers

    Which fatty acid is classified as a monounsaturated fatty acid?

    <p>Oleic acid</p> Signup and view all the answers

    What reaction do fatty acids undergo similar to other carboxylic acids?

    <p>Esterification</p> Signup and view all the answers

    Which of the following fatty acids is known for decreasing heart disease risk?

    <p>Palmitoleic acid</p> Signup and view all the answers

    What happens to the solubility of fatty acids in water as their chain length increases?

    <p>It decreases</p> Signup and view all the answers

    What indicates the presence of double bonds in an unsaturated fatty acid's notation?

    <p>Greek capital letter delta (∆)</p> Signup and view all the answers

    Which fatty acid is a saturated fatty acid with 18 carbons?

    <p>Stearic acid</p> Signup and view all the answers

    Which fatty acid is commonly found in fish oils?

    <p>Gadoleic acid</p> Signup and view all the answers

    Which type of fat is referred to as 'bad cholesterol'?

    <p>Saturated fats</p> Signup and view all the answers

    What characterizes the structure of saturated fatty acids?

    <p>Single bonds between carbon atoms</p> Signup and view all the answers

    What is the process called that results in the breaking of 1-2 ester bonds in triacylglycerols?

    <p>Hydrolysis</p> Signup and view all the answers

    What does rancidity primarily result from?

    <p>Bacterial enzyme activity</p> Signup and view all the answers

    Which of the following describes saponification?

    <p>Hydrolysis in basic solution</p> Signup and view all the answers

    What type of lipids primarily form the structural components of biological membranes?

    <p>Glycerophospholipids</p> Signup and view all the answers

    What is the effect of hydrogenation on unsaturated fatty acids?

    <p>They are converted to saturated fatty acids.</p> Signup and view all the answers

    What is the primary function of phospholipids in cell membranes?

    <p>Serve as structural components</p> Signup and view all the answers

    How are fats and oils typically hydrolyzed to prepare soap?

    <p>Under high pressure and high temperature with sodium carbonate</p> Signup and view all the answers

    What occurs during the oxidation of triacylglycerols?

    <p>Breakage of double bonds</p> Signup and view all the answers

    What is the primary type of energy storage material in human cells?

    <p>Carbohydrate glycogen</p> Signup and view all the answers

    What is the main characteristic of triglycerides?

    <p>They are hydrophobic substances.</p> Signup and view all the answers

    Which type of lipid is characterized by its solid state at room temperature?

    <p>Waxes</p> Signup and view all the answers

    Which type of triacylglycerol contains more than one kind of fatty acid?

    <p>Mixed triacylglycerols</p> Signup and view all the answers

    What is the outcome of hydrolysis of triacylglycerols within the human body?

    <p>Production of mono- or diacylglycerols and fatty acids</p> Signup and view all the answers

    What distinguishes fats from oils?

    <p>Fats are primarily solids or semisolids and oils are predominantly liquids at room temperature.</p> Signup and view all the answers

    What is the recommended dietary intake for monounsaturated fat in calories?

    <p>15%</p> Signup and view all the answers

    Which of the following is a chemical reaction associated with triacylglycerols?

    <p>Saponification</p> Signup and view all the answers

    Which function groups give triacylglycerols their chemical properties?

    <p>Esters and Alkenes</p> Signup and view all the answers

    Which process involves adding hydrogen to unsaturated fats to increase saturation?

    <p>Hydrogenation</p> Signup and view all the answers

    What typically occurs to fats over time when exposed to air or moisture?

    <p>They undergo rancidity.</p> Signup and view all the answers

    Which of the following statements is true about stored triglycerides?

    <p>They should be fluid at body temperature.</p> Signup and view all the answers

    What is the effect of increasing cis double bonds in fatty acids?

    <p>Decreases melting point</p> Signup and view all the answers

    Which fatty acid is known for being a source in corn oil and animal tissues?

    <p>Linoleic acid</p> Signup and view all the answers

    What is a characteristic of trans fatty acids?

    <p>They are a minor product of metabolism in both plants and animals</p> Signup and view all the answers

    What happens to the solubility of fatty acids as their chain length increases?

    <p>It decreases</p> Signup and view all the answers

    Which of the following fatty acids has the highest number of double bonds?

    <p>Docosahexaenoic acid</p> Signup and view all the answers

    Which option correctly describes the relationship between chain length and melting point of fatty acids?

    <p>Increased chain length raises melting point</p> Signup and view all the answers

    What is the primary purpose of synthetic trans fats created through hydrogenation?

    <p>To increase the melting point and improve stability</p> Signup and view all the answers

    How does the presence of bends in a fatty acid chain influence its physical state at room temperature?

    <p>It tends to make them liquids at room temperature</p> Signup and view all the answers

    What is the primary role of leukotrienes in the body?

    <p>Promoting inflammatory and hypersensitivity responses</p> Signup and view all the answers

    How do COX-2 inhibitors function in relation to inflammation?

    <p>They selectively inhibit COX-2 enzymes</p> Signup and view all the answers

    Which of the following is NOT a typical effect of nonsteroidal anti-inflammatory drugs (NSAIDs)?

    <p>Causing excessive weight gain</p> Signup and view all the answers

    What ingredients primarily compose leukotrienes?

    <p>C20 fatty acids</p> Signup and view all the answers

    What is the main purpose of utilizing COX-2 inhibitors in medical treatments?

    <p>To selectively reduce inflammation</p> Signup and view all the answers

    What are glycerophospholipids primarily composed of?

    <p>A glycerol backbone, two fatty acid tails, and a phosphate head group</p> Signup and view all the answers

    Which glycerophospholipid is often found in the inner leaflet of the membrane?

    <p>Phosphatidylserine</p> Signup and view all the answers

    What is the simplest form of sphingoglycolipid?

    <p>Cerebrosides</p> Signup and view all the answers

    What distinguishes sphingomyelin from other sphingolipids?

    <p>It has a phosphate head group instead of a sugar moiety</p> Signup and view all the answers

    What type of sphingolipid contains only neutral sugars?

    <p>Neutral glycosphingolipids</p> Signup and view all the answers

    Which of the following is a characteristic of cholesterol?

    <p>It is a component of biomembranes.</p> Signup and view all the answers

    What is a major characteristic of gangliosides?

    <p>They contain sialic acid residues linked to the sugar</p> Signup and view all the answers

    Which reaction can be used to estimate cholesterol levels?

    <p>Liebermann-Burchard reaction</p> Signup and view all the answers

    What is a significant role of cholesterol in the human body?

    <p>It neutralizes the hemolytic action of toxins.</p> Signup and view all the answers

    What is the role of phosphatidylinositol in cell membranes?

    <p>Involved in cell signaling and membrane trafficking</p> Signup and view all the answers

    What defines the primary function of glycerophospholipids in membranes?

    <p>Making up the structural backbone</p> Signup and view all the answers

    What is unique about the structure of cholesterol?

    <p>It has a fused ring structure with three 6-carbon rings and one 5-carbon ring.</p> Signup and view all the answers

    Which lipids are known to contain a sugar attached to sphingosine?

    <p>Sphingolipids</p> Signup and view all the answers

    Cholesterol can be derived from which of the following substances?

    <p>Isoprene</p> Signup and view all the answers

    Which statement is true about cerebrosides?

    <p>They primarily occur in the brain.</p> Signup and view all the answers

    Which of the following is a common dietary source of phosphatidylcholine?

    <p>Egg yolk</p> Signup and view all the answers

    Which lipid class is primarily associated with the cell membrane and includes sphingomyelin?

    <p>Sphingolipids</p> Signup and view all the answers

    What effect do polyunsaturated acids have on plasma cholesterol levels?

    <p>Lower plasma cholesterol levels</p> Signup and view all the answers

    Which component is not associated with the structure of cholesterol?

    <p>Glycerol</p> Signup and view all the answers

    In which part of the body is cholesterol NOT synthesized?

    <p>Pancreas</p> Signup and view all the answers

    What is the primary role of bile acids in digestion?

    <p>To facilitate the absorption of lipids.</p> Signup and view all the answers

    Which statement accurately describes steroid hormones?

    <p>They consist of a fused-ring structure.</p> Signup and view all the answers

    What physiological effects do eicosanoids typically have?

    <p>They exert significant effects at low concentrations.</p> Signup and view all the answers

    Which hormone is classified under glucocorticoids?

    <p>Cortisol</p> Signup and view all the answers

    What is a primary function of prostaglandins?

    <p>Regulate body temperature.</p> Signup and view all the answers

    What do mineralocorticoids primarily regulate?

    <p>Ion balances</p> Signup and view all the answers

    Which eicosanoid is involved in promoting platelet aggregation?

    <p>Thromboxane</p> Signup and view all the answers

    Which of the following is a characteristic of steroid hormones?

    <p>Derive from cholesterol.</p> Signup and view all the answers

    How do eicosanoids generally operate in the body?

    <p>Act only in the tissues where they are synthesized.</p> Signup and view all the answers

    What is the role of bile acids in stimulating bile flow?

    <p>They stimulate more bile secretion by the liver.</p> Signup and view all the answers

    What is a significant role of leukotrienes in the human body?

    <p>They promote inflammatory and hypersensitivity responses.</p> Signup and view all the answers

    What distinguishes COX-2 inhibitors from conventional NSAIDs?

    <p>They selectively inhibit COX-2 to reduce inflammation with fewer side effects.</p> Signup and view all the answers

    Which outcome is most likely due to the inhibition of COX enzymes by NSAIDs?

    <p>Reduction in pain, inflammation, and fever.</p> Signup and view all the answers

    What characteristic best describes the structure of leukotrienes?

    <p>They are derivatives of c20 fatty acids with three conjugated double bonds and hydroxyl groups.</p> Signup and view all the answers

    Which clinical significance is associated with the use of selective COX-2 inhibitors?

    <p>They lessen the impact of gastrointestinal disturbances compared to COX-1 inhibitors.</p> Signup and view all the answers

    Which of the following fatty acids contains more than one carbon-carbon double bond?

    <p>Arachidonic acid</p> Signup and view all the answers

    How does the presence of cis double bonds affect the melting point of fatty acids?

    <p>Decreases melting point</p> Signup and view all the answers

    Which of the following fatty acids is primarily sourced from brain tissue?

    <p>Docosahexaenoic acid</p> Signup and view all the answers

    What is the impact of increasing chain length on the solubility of fatty acids?

    <p>Decreases solubility</p> Signup and view all the answers

    Which fatty acid is associated with increased melting point due to even-numbered carbon atoms?

    <p>Stearic acid</p> Signup and view all the answers

    Which of the following statements about trans fatty acids is true?

    <p>They are produced during the hydrogenation of unsaturated fats.</p> Signup and view all the answers

    What is the typical effect of multiple double bonds on the physical state of fatty acids at room temperature?

    <p>Makes them liquid</p> Signup and view all the answers

    Which fatty acid is a typical source of omega-6 fatty acids found in corn oil?

    <p>Linoleic acid</p> Signup and view all the answers

    What is the primary source of cholesterol production in the human body?

    <p>Liver</p> Signup and view all the answers

    Which of the following statements is true regarding dietary cholesterol?

    <p>Cholesterol consumption does not affect its synthesis.</p> Signup and view all the answers

    What percentage of cell membranes is comprised of cholesterol by mass?

    <p>25%</p> Signup and view all the answers

    How are lipoproteins primarily characterized?

    <p>Conjugated proteins that transport lipids to tissues.</p> Signup and view all the answers

    Which of the following conditions is NOT directly associated with cholesterol levels?

    <p>Chronic pancreatitis</p> Signup and view all the answers

    What role does cholesterol play in nerve and brain tissue?

    <p>It accounts for 10% of dry mass.</p> Signup and view all the answers

    Which of the following statements accurately describes the relationship between cholesterol and cardiovascular disease?

    <p>Excess intake of cholesterol may lead to cardiovascular issues.</p> Signup and view all the answers

    Which food source is noted for having no cholesterol?

    <p>Plant-based foods</p> Signup and view all the answers

    What is the typical daily synthesis of cholesterol by the liver?

    <p>800-1000 mg</p> Signup and view all the answers

    What is the approximate amount of cholesterol present in every 100 ml of blood plasma?

    <p>50 mg</p> Signup and view all the answers

    What is the primary product formed from the hydrolysis of triacylglycerols?

    <p>Fatty acids and mono- or diacylglycerol</p> Signup and view all the answers

    During the hydrogenation of unsaturated fatty acids, which chemical structure is primarily altered?

    <p>Carbon-carbon double bonds</p> Signup and view all the answers

    What effect does oxidation have on triacylglycerols when exposed to oxygen?

    <p>Formation of aldehydes or carboxylic acids</p> Signup and view all the answers

    What is a common method used to prepare soap through saponification?

    <p>Hydrolyzing fats with sodium carbonate</p> Signup and view all the answers

    What is the role of phospholipids in biological membranes?

    <p>Structural support and transport</p> Signup and view all the answers

    Which statement best describes hydrolytic rancidity?

    <p>Result of lipase action from bacteria</p> Signup and view all the answers

    What is the primary structural characteristic of waxes?

    <p>Esters of long-chain fatty acids and alcohols</p> Signup and view all the answers

    Which class of lipids is most abundant in cell membranes, comprising up to 80% of their mass?

    <p>Glycerophospholipids</p> Signup and view all the answers

    What is typically not a result of oxidation in unsaturated triacylglycerols?

    <p>Saturation of fatty acids</p> Signup and view all the answers

    In the context of biological membranes, what is the primary function of sterols like cholesterol?

    <p>Maintaining membrane fluidity and stability</p> Signup and view all the answers

    What is the primary role of bile acids in lipid digestion?

    <p>Facilitating the absorption of dietary fats</p> Signup and view all the answers

    Which lipid class derives its structure from arachidonic acid?

    <p>Eicosanoids</p> Signup and view all the answers

    Which of the following steroid hormones is primarily involved in regulating ion balances in the body?

    <p>Aldosterone</p> Signup and view all the answers

    What is a common effect of prostaglandins in the human body?

    <p>Raising body temperature</p> Signup and view all the answers

    Which property distinguishes eicosanoids from classical hormones?

    <p>They act locally at the synthesis site</p> Signup and view all the answers

    Which of the following is NOT a structure of steroid hormones?

    <p>Linear structure with multiple branches</p> Signup and view all the answers

    What physiological response is primarily associated with thromboxanes?

    <p>Encouraging platelet aggregation</p> Signup and view all the answers

    Which vitamin absorption is directly facilitated by bile acids?

    <p>Vitamin K</p> Signup and view all the answers

    What components do mixed micelles transport to the intestinal mucosa?

    <p>Lipids and fat-soluble vitamins</p> Signup and view all the answers

    Which of the following steroid hormones is NOT considered a glucocorticoid?

    <p>Aldosterone</p> Signup and view all the answers

    What primarily distinguishes lipids from other biomolecules?

    <p>Insolubility in water and solubility in non-polar solvents</p> Signup and view all the answers

    Which category of lipids serves as chemical messengers in the body?

    <p>Steroids and eicosanoids</p> Signup and view all the answers

    What is one of the main functions of triacylglycerols in living organisms?

    <p>Acting as major metabolic fuels and energy storage</p> Signup and view all the answers

    Which of the following statements about phospholipids is true?

    <p>They have a hydrophilic head and hydrophobic tails.</p> Signup and view all the answers

    What is the biological significance of fats in the body?

    <p>They provide insulation and padding for internal organs.</p> Signup and view all the answers

    Which lipid type is categorized as a protective-coating lipid?

    <p>Waxes</p> Signup and view all the answers

    In which category of lipids would bile acids fall?

    <p>Emulsifying lipids</p> Signup and view all the answers

    Which lipid is noted for its role in participating in signal transduction pathways?

    <p>Phospholipids</p> Signup and view all the answers

    What type of lipids are involved in the formation of micelles to aid in lipid absorption?

    <p>Bile acids</p> Signup and view all the answers

    Which of the following is NOT a function of eicosanoids?

    <p>Facilitating lipid digestion</p> Signup and view all the answers

    What hormone is characterized as a glucocorticoid and is known for suppressing inflammatory reactions?

    <p>Cortisol</p> Signup and view all the answers

    Which statement accurately describes the structural characteristics of steroid hormones?

    <p>They consist of a fused-ring structure with three six-membered rings and one five-membered ring.</p> Signup and view all the answers

    Which effect is associated with the action of prostaglandins?

    <p>Increasing the secretion of protective mucus in the stomach</p> Signup and view all the answers

    What is produced as a result of saponification?

    <p>Glycerol and fatty acid salts</p> Signup and view all the answers

    Which of the following accurately describes the process of oxidation in triacylglycerols?

    <p>Breakage of C=C bonds leading to smaller molecules</p> Signup and view all the answers

    What characterizes hydrolytic rancidity?

    <p>Chemical reaction with moisture leading to fat breakdown</p> Signup and view all the answers

    What is the primary role of glycerophospholipids in cell membranes?

    <p>Structural components of the membrane</p> Signup and view all the answers

    What is the primary difference between saturated and unsaturated fatty acids?

    <p>Saturated fatty acids have a higher melting point</p> Signup and view all the answers

    Which of the following is a characteristic of waxes?

    <p>Hydrophobic and water-repellent</p> Signup and view all the answers

    What occurs when double bonds in unsaturated fatty acids react with hydrogen gas?

    <p>Hydrogenation leading to saturated fatty acids</p> Signup and view all the answers

    How are most soaps prepared today?

    <p>By hydrolyzing fats under high pressure and temperature</p> Signup and view all the answers

    What is the main chemical reaction associated with the breakdown of triacylglycerols in the body?

    <p>Hydrolysis</p> Signup and view all the answers

    Which fatty acid is classified as having three double bonds in its structure?

    <p>Linolenic acid</p> Signup and view all the answers

    What effect do trans fatty acids have on melting points compared to cis fatty acids?

    <p>Trans fatty acids have melting points similar to saturated fats.</p> Signup and view all the answers

    Which of the following fatty acids is primarily found in phospholipids?

    <p>5,8,11-eicosatrienoic acid</p> Signup and view all the answers

    What is a characteristic feature of polyunsaturated fatty acids?

    <p>Contain more than one carbon-carbon double bond.</p> Signup and view all the answers

    Which fatty acid is commonly associated with corn oil?

    <p>Linoleic acid</p> Signup and view all the answers

    How does the presence of cis double bonds affect the physical state of fatty acids at room temperature?

    <p>They often result in fatty acids being liquid.</p> Signup and view all the answers

    What impact does chain length have on the solubility of fatty acids?

    <p>Longer chains are less soluble in water.</p> Signup and view all the answers

    Which statement is true regarding the melting points of saturated versus unsaturated fatty acids?

    <p>Odd-numbered saturated fatty acids have higher melting points than even-numbered.</p> Signup and view all the answers

    What is the primary reason for the partial hydrogenation of fats?

    <p>To enhance freshness and improve stability.</p> Signup and view all the answers

    Which fatty acid is known to have a structure characterized by four double bonds?

    <p>Arachidonic acid</p> Signup and view all the answers

    What characterizes saturated fatty acids compared to unsaturated fatty acids?

    <p>Have maximum hydrogen atoms bonded to each carbon</p> Signup and view all the answers

    Which fatty acid is associated with having a positive effect on heart disease risk?

    <p>Oleic acid</p> Signup and view all the answers

    What distinguishes the solubility of fatty acids in water based on their chain length?

    <p>Longer-chain fatty acids have little effect on pH</p> Signup and view all the answers

    Which characteristic is true about a fatty acid with the notation 18:2?

    <p>It contains 18 carbons and 2 double bonds</p> Signup and view all the answers

    Which type of fatty acid is typically solid at room temperature?

    <p>Saturated fatty acids</p> Signup and view all the answers

    What effect does the presence of double bonds have on the melting point of fatty acids?

    <p>Decreases the melting point</p> Signup and view all the answers

    Which fatty acid is known as n-dodecanoic acid?

    <p>Lauric acid</p> Signup and view all the answers

    Which fatty acid primarily found in animal lipids is classified as saturated?

    <p>Palmitic acid</p> Signup and view all the answers

    How does the structure of a saturated fatty acid differ from that of a monounsaturated fatty acid?

    <p>Saturated fatty acids have more hydrogen atoms</p> Signup and view all the answers

    What is associated with the solubility behavior of fatty acids in water?

    <p>Length and branching of the carbon chain</p> Signup and view all the answers

    What distinguishes lipids from other biomolecules?

    <p>They are organic compounds that are insoluble in water.</p> Signup and view all the answers

    Which of the following lipids serves as a building block for cellular membranes?

    <p>Cholesterol</p> Signup and view all the answers

    What is the primary function of fatty acids in biological systems?

    <p>They act as energy storage molecules.</p> Signup and view all the answers

    Which category of lipids includes steroids and eicosanoids?

    <p>Chemical messenger lipids</p> Signup and view all the answers

    How do lipids contribute to the absorption of fat-soluble vitamins?

    <p>They emulsify lipids to improve their solubility.</p> Signup and view all the answers

    What role do lipoproteins play in the body?

    <p>They transport lipids in the bloodstream.</p> Signup and view all the answers

    Which of the following describes the structure of phospholipids?

    <p>They contain a phosphate group along with fatty acid tails.</p> Signup and view all the answers

    What is the primary source of metabolic fuel from fats?

    <p>Fatty acids from triacylglycerols.</p> Signup and view all the answers

    What state are saturated fatty acids typically found in at room temperature?

    <p>Solid</p> Signup and view all the answers

    Which fatty acid is associated with a dietary decrease in heart disease risk?

    <p>Oleic acid</p> Signup and view all the answers

    What characterizes the structural composition of saturated fatty acids?

    <p>Unbranched linear chains with carbon-carbon single bonds</p> Signup and view all the answers

    How do longer-chain fatty acids affect the pH of an aqueous solution?

    <p>They have little effect on the pH</p> Signup and view all the answers

    Which notation indicates the presence of double bonds in an unsaturated fatty acid?

    <p>Greek letter delta (∆) with superscript numbers</p> Signup and view all the answers

    What type of fatty acid is typically liquid at room temperature?

    <p>Monounsaturated fatty acid</p> Signup and view all the answers

    What is a common source of myristic acid?

    <p>Nutmeg</p> Signup and view all the answers

    What kind of fatty acids are indicated by a notation of 18:2?

    <p>Unsaturated fatty acids</p> Signup and view all the answers

    Which fatty acid is primarily found in animal tissues and is known for having 18 carbons?

    <p>Oleic acid</p> Signup and view all the answers

    What is the effect of increasing carbon chain length in fatty acids on their solubility in water?

    <p>Decreases solubility gradually</p> Signup and view all the answers

    What is the primary role of leukotrienes in the body?

    <p>Promoting inflammatory and hypersensitivity responses</p> Signup and view all the answers

    What is the action of COX-2 inhibitors compared to conventional NSAIDs?

    <p>They selectively inhibit COX-2 to reduce inflammation</p> Signup and view all the answers

    What is a characteristic feature of eicosanoids related to inflammation?

    <p>They are derived from the metabolism of arachidonic acid</p> Signup and view all the answers

    Which of the following is a potential benefit of selective COX-2 inhibitors over traditional NSAIDs?

    <p>Lower risk of stomach bleeding and ulcers</p> Signup and view all the answers

    What compound do NSAIDs primarily inhibit to achieve their therapeutic effects?

    <p>COX enzymes</p> Signup and view all the answers

    What is the primary role of lipase in the human body?

    <p>To hydrolyze triacylglycerols</p> Signup and view all the answers

    Which statement best describes the process of saponification?

    <p>The hydrolysis of fats and oils in a basic solution</p> Signup and view all the answers

    What do the oxidation of triacylglycerols primarily lead to?

    <p>The production of short-chain aldehydes</p> Signup and view all the answers

    Hydrolytic rancidity occurs mainly due to what factor?

    <p>Partial hydrolysis by bacterial enzymes</p> Signup and view all the answers

    What is a common characteristic of waxes?

    <p>They are solid at room temperature</p> Signup and view all the answers

    Which class of lipids forms the bilayer matrix of biological membranes?

    <p>Phospholipids</p> Signup and view all the answers

    Which process is involved in converting unsaturated fatty acids into saturated fatty acids?

    <p>Hydrogenation</p> Signup and view all the answers

    What is a key function of phospholipids in cell membranes?

    <p>Acting as structural components</p> Signup and view all the answers

    Which of the following best describes the process of hydrolysis of triacylglycerols?

    <p>It forms free fatty acids and glycerol.</p> Signup and view all the answers

    What is the impact of exposing fats and oils to air and moisture over time?

    <p>They lead to rancidity.</p> Signup and view all the answers

    What role do bile acids play in lipid digestion?

    <p>They transport lipids to the intestinal mucosa.</p> Signup and view all the answers

    Which type of hormones is primarily derived from cholesterol?

    <p>Steroid hormones</p> Signup and view all the answers

    What is the primary function of prostaglandins?

    <p>Involving in various physiological processes like pain and inflammation.</p> Signup and view all the answers

    What characteristic is unique to eicosanoids compared to other hormones?

    <p>They are synthesized and exert effects locally.</p> Signup and view all the answers

    Which steroid hormone is known for promoting female sex characteristics?

    <p>Estradiol</p> Signup and view all the answers

    What is the effect of bile acids on fat-soluble vitamins in the intestine?

    <p>They facilitate their absorption.</p> Signup and view all the answers

    Which of the following statements is true about mineralocorticoids?

    <p>They regulate ion balances like Na+ and K+.</p> Signup and view all the answers

    What type of fatty acid derivative is known for promoting platelet aggregation?

    <p>Thromboxanes</p> Signup and view all the answers

    In what way do eicosanoids differ from traditional hormones?

    <p>Eicosanoids operate only in the tissues they are synthesized.</p> Signup and view all the answers

    Which example of glucocorticoid is important for glucose synthesis and immune response suppression?

    <p>Cortisol</p> Signup and view all the answers

    What defines a lipid in terms of solubility?

    <p>Insoluble in both water and polar organic solvents</p> Signup and view all the answers

    Which function does NOT describe the role of lipids?

    <p>Playing roles in structural integrity of nucleic acids</p> Signup and view all the answers

    What is the primary role of leukotrienes in the body?

    <p>Stimulating inflammatory responses</p> Signup and view all the answers

    How do COX-2 inhibitors differ from conventional NSAIDs regarding their effects?

    <p>They reduce fever and inflammation without affecting COX-1.</p> Signup and view all the answers

    Which statement accurately describes phospholipids?

    <p>They are integral to the structure of biological membranes.</p> Signup and view all the answers

    What is a characteristic property of cholesterol?

    <p>It is a precursor for steroid hormones.</p> Signup and view all the answers

    What impact do NSAIDs have on eicosanoid production?

    <p>They inhibit the production of eicosanoids.</p> Signup and view all the answers

    Which characteristic is true about leukotrienes?

    <p>They contain multiple conjugated double bonds.</p> Signup and view all the answers

    Which of the following lipids is classified as a protective-coating lipid?

    <p>Waxes</p> Signup and view all the answers

    What is the primary role of lipoproteins in the body?

    <p>Transporting fats and cholesterol in the bloodstream</p> Signup and view all the answers

    What is a significant clinical application of COX-2 inhibitors?

    <p>To provide a safer option for managing pain and inflammation.</p> Signup and view all the answers

    Which type of fatty acid is most commonly found in biological systems?

    <p>Fatty acids with an even number of carbon atoms</p> Signup and view all the answers

    Which function do messenger lipids primarily serve in the body?

    <p>Facilitating cell signaling and communication</p> Signup and view all the answers

    What is the primary structural characteristic of saturated fatty acids?

    <p>They consist of unbranched, linear chains.</p> Signup and view all the answers

    Which fatty acid is known to decrease the risk of heart disease?

    <p>Oleic acid</p> Signup and view all the answers

    What happens to the acidity of fatty acids as the chain length increases?

    <p>The acidity decreases.</p> Signup and view all the answers

    Which fatty acid is classified as a saturated fatty acid with 16 carbons?

    <p>Palmitic acid</p> Signup and view all the answers

    How does the solubility of fatty acids in water change with increasing chain length?

    <p>Solubility decreases.</p> Signup and view all the answers

    What does the notation 18:2 indicate in relation to an unsaturated fatty acid?

    <p>18 carbons and 2 double bonds</p> Signup and view all the answers

    What is the typical state of saturated fatty acids at room temperature?

    <p>Solid</p> Signup and view all the answers

    Which of the following statements is true regarding the properties of unsaturated fatty acids?

    <p>They are liquid at room temperature.</p> Signup and view all the answers

    What role do conjugate bases of fatty acids play in near neutral pH environments?

    <p>They do not significantly affect the pH.</p> Signup and view all the answers

    What is the predominant type of energy storage material found in human cells?

    <p>Glycogen</p> Signup and view all the answers

    Which type of triacylglycerol consists of three identical fatty acids?

    <p>Simple triacylglycerols</p> Signup and view all the answers

    What is the main characteristic of triglycerides?

    <p>They are primarily viscous oils when melted.</p> Signup and view all the answers

    What property do triglycerides exhibit due to the absence of electric charges?

    <p>They are referred to as neutral lipids.</p> Signup and view all the answers

    Which type of fats are predominantly liquid at room temperature?

    <p>Oils</p> Signup and view all the answers

    What is one of the primary roles of dietary fats in a balanced diet?

    <p>To contribute to total caloric intake.</p> Signup and view all the answers

    What chemical process involves the breaking of ester bonds in triacylglycerols?

    <p>Saponification</p> Signup and view all the answers

    What type of dietary fat is currently recommended to make up approximately 10% of total caloric intake?

    <p>Polyunsaturated fat</p> Signup and view all the answers

    What is a feature that distinguishes fats from oils?

    <p>Fats have a higher melting point.</p> Signup and view all the answers

    What type of fatty acids are generally included in triglycerides?

    <p>More than one type of fatty acid</p> Signup and view all the answers

    What is the backbone structure of glycerophospholipids?

    <p>Glycerol</p> Signup and view all the answers

    Which phospholipid is commonly found in the inner leaflet of cell membranes?

    <p>Phosphatidylserine</p> Signup and view all the answers

    What characterizes sphingomyelin among sphingolipids?

    <p>It is a major component of biological membranes.</p> Signup and view all the answers

    What role do neutral glycosphingolipids play in the cell membrane?

    <p>They act as antigens and receptors.</p> Signup and view all the answers

    Which glycerophospholipid is especially noted for its role in cell signaling?

    <p>Phosphatidylinositol</p> Signup and view all the answers

    What is a defining feature of gangliosides?

    <p>They contain one or more sialic acid residues.</p> Signup and view all the answers

    Which dietary source is particularly high in phosphatidylcholine?

    <p>Egg yolk</p> Signup and view all the answers

    How do sphingolipids differ in structure from glycerophospholipids?

    <p>Sphingolipids contain a sugar moiety.</p> Signup and view all the answers

    What is the primary function of phosphatidylcholine in cell membranes?

    <p>Creating structural integrity</p> Signup and view all the answers

    What type of lipid is primarily found in brain tissue, accounting for 7% of its dry mass?

    <p>Neutral glycosphingolipids</p> Signup and view all the answers

    Which statement correctly defines lipids?

    <p>Lipids are organic compounds that are insoluble in water but soluble in non-polar organic solvents.</p> Signup and view all the answers

    What is the primary biological significance of fats?

    <p>They serve as reserves of metabolic energy and insulation.</p> Signup and view all the answers

    Which of the following best describes the function of bile acids in lipid absorption?

    <p>Bile acids create micelles that transport lipids to the intestinal mucosa.</p> Signup and view all the answers

    Which type of lipid is classified as a membrane lipid?

    <p>Phospholipids</p> Signup and view all the answers

    Which of the following accurately describes the function of cholesterol?

    <p>Cholesterol is a precursor for steroid hormones and vital for cell membrane structure.</p> Signup and view all the answers

    Which type of hormone is specifically categorized as a lipid and is derived from cholesterol?

    <p>Steroid hormones</p> Signup and view all the answers

    What role do lipoproteins play in the body?

    <p>Lipoproteins help in the transport of lipids through the bloodstream.</p> Signup and view all the answers

    What is the primary physiological effect of prostaglandins?

    <p>Regulating body temperature and enhancing inflammation responses.</p> Signup and view all the answers

    Which property is common to both triglycerides and phospholipids?

    <p>Both contain glycerol as a backbone.</p> Signup and view all the answers

    Which hormone among the following primarily regulates ion balances in the body?

    <p>Aldosterone</p> Signup and view all the answers

    How do eicosanoids exert their effects within the body?

    <p>By exerting effects in the tissues where they are synthesized.</p> Signup and view all the answers

    Which class of lipids includes cholesterol and steroid hormones?

    <p>Steroids</p> Signup and view all the answers

    What is the main characteristic of fatty acids?

    <p>They can be saturated or unsaturated depending on hydrogen saturation.</p> Signup and view all the answers

    What is the primary role of cholesterol in human cell membranes?

    <p>Acts as a structural component</p> Signup and view all the answers

    How much cholesterol is typically synthesized by the human liver each day?

    <p>800-1000 mg</p> Signup and view all the answers

    Which type of food contains no cholesterol?

    <p>Plant-based food</p> Signup and view all the answers

    How does the ingestion of dietary cholesterol affect the body's cholesterol synthesis?

    <p>It decreases cholesterol synthesis.</p> Signup and view all the answers

    What is the main function of lipoproteins in the body?

    <p>Transport lipids in the blood</p> Signup and view all the answers

    What is a common characteristic of saturated fatty acids?

    <p>Solid at room temperature</p> Signup and view all the answers

    What percentage of dry mass in nerve and brain tissue is cholesterol?

    <p>10%</p> Signup and view all the answers

    Which fatty acid is known for its potential heart disease risk reduction?

    <p>Oleic acid</p> Signup and view all the answers

    What can result from a significant decrease in cholesterol synthesis without adequate dietary intake?

    <p>Cardiovascular disease</p> Signup and view all the answers

    What condition is caused by the accumulation of plaque around arteries due to excess cholesterol?

    <p>Atherosclerosis</p> Signup and view all the answers

    What occurs to the solubility of fatty acids as their chain length increases?

    <p>Decreases in solubility</p> Signup and view all the answers

    Which option describes the relationship of cholesterol with daily dietary requirements?

    <p>Synthesized amounts are sufficient.</p> Signup and view all the answers

    How are unsaturated fatty acids structurally indicated in notation?

    <p>With a capital letter delta (∆) and superscript numbers</p> Signup and view all the answers

    Which characteristic is NOT true for unsaturated fatty acids?

    <p>They typically contain more hydrogen atoms</p> Signup and view all the answers

    What type of disorder is xanthomatosis associated with?

    <p>Fat storage disorders</p> Signup and view all the answers

    Which fatty acid is an example of a long-chain saturated fatty acid?

    <p>Stearic acid</p> Signup and view all the answers

    What distinguishes saturated fatty acids from unsaturated fatty acids?

    <p>Saturated fatty acids have only single carbon bonds.</p> Signup and view all the answers

    What is the typical effect of increasing the number of double bonds in unsaturated fatty acids on their melting point?

    <p>Decreases the melting point</p> Signup and view all the answers

    Which of the following fatty acids has 22 carbons and is categorized as a saturated fatty acid?

    <p>Behenic acid</p> Signup and view all the answers

    What effect does the presence of a terminal carboxylic acid group have on fatty acids?

    <p>Allows them to form esters</p> Signup and view all the answers

    Which lipoprotein type has the lowest density and is primarily responsible for transporting dietary lipids?

    <p>Chylomicrons</p> Signup and view all the answers

    What is the primary function of bile acids in digestion?

    <p>Reducing the surface tension of fat droplets</p> Signup and view all the answers

    Which of the following components is NOT typically found in chylomicrons?

    <p>Free amino acids</p> Signup and view all the answers

    What characteristic of bile acids increases their solubility in water?

    <p>Multiple hydroxyl groups</p> Signup and view all the answers

    Which lipoprotein has a density range between 1.006-1.063 g/ml and is associated with transporting cholesterol from the liver to peripheral tissues?

    <p>Low-density lipoproteins (LDL)</p> Signup and view all the answers

    What type of sterol is primarily found in animals, serving as a major component of biological membranes?

    <p>Cholesterol</p> Signup and view all the answers

    Which molecule is conjugated with bile acids to increase their solubility and neutralize acidity?

    <p>Glycine or taurine</p> Signup and view all the answers

    What is the main role of HDL (High-density lipoprotein) in lipid transport?

    <p>Removing excess cholesterol from tissues</p> Signup and view all the answers

    In which human organ are bile acids primarily synthesized from cholesterol?

    <p>Liver</p> Signup and view all the answers

    Which of the following lipoproteins is primarily responsible for the transport of triglycerides from the liver to tissues?

    <p>Very low-density lipoprotein (VLDL)</p> Signup and view all the answers

    What type of fatty acids have more than one carbon-carbon double bond?

    <p>Polyunsaturated fatty acids</p> Signup and view all the answers

    What characteristic of fatty acids causes a decrease in melting point?

    <p>Presence of cis double bonds</p> Signup and view all the answers

    Which of the following fatty acids is known for being present in brain tissue?

    <p>Arachidonic acid</p> Signup and view all the answers

    How does the melting point of fatty acids change with chain length?

    <p>It increases with increasing chain length</p> Signup and view all the answers

    Trans fatty acids are primarily produced through which process?

    <p>Partial hydrogenation of fats</p> Signup and view all the answers

    Which fatty acid is classified as having 18 carbons and two double bonds?

    <p>Linoleic acid</p> Signup and view all the answers

    What effect does an increase in the number of double bonds in a fatty acid chain have?

    <p>Decreases melting point</p> Signup and view all the answers

    Which of the following is a typical source of linolenic acid?

    <p>Animal tissues</p> Signup and view all the answers

    What is the main function of bile acids in the digestive system?

    <p>To transport lipids for absorption in the intestines</p> Signup and view all the answers

    Which type of hormone is classified as a lipid and acts as a chemical messenger?

    <p>Eicosanoids</p> Signup and view all the answers

    Which of the following steroid hormones is known for regulating blood pressure and ion balances?

    <p>Aldosterone</p> Signup and view all the answers

    What is a key role of prostaglandins in the body?

    <p>Raising body temperature and aiding in inflammation responses</p> Signup and view all the answers

    What characteristic do eicosanoids possess regarding their physiological effects?

    <p>They exert effects locally at extremely low concentrations</p> Signup and view all the answers

    What is the primary energy storage material in human cells?

    <p>Glycogen</p> Signup and view all the answers

    Which type of triacylglycerol is formed from the esterification of glycerol with more than one kind of fatty acid?

    <p>Mixed triacylglycerol</p> Signup and view all the answers

    What describes the general state of oils at room temperature?

    <p>Liquids</p> Signup and view all the answers

    Which of the following statements about triglycerides is true?

    <p>They are formed from glycerol and fatty acids.</p> Signup and view all the answers

    What type of dietary fat should comprise 10% of total fat intake according to current recommendations?

    <p>Polyunsaturated fat</p> Signup and view all the answers

    Which process involves the breaking of ester bonds in triacylglycerols?

    <p>Hydrolysis</p> Signup and view all the answers

    What is a characteristic of triglycerides at body temperature?

    <p>They are generally very viscous oils.</p> Signup and view all the answers

    Which of the following describes the main characteristic of triacylglycerols?

    <p>They possess no electric charges.</p> Signup and view all the answers

    What is the key distinction between fats and oils?

    <p>Fats are solids or semisolids, while oils are predominantly liquids.</p> Signup and view all the answers

    What does hydrogenation of fats involve?

    <p>Adding hydrogen to unsaturated fats.</p> Signup and view all the answers

    What is the primary role of cholesterol in human cell membranes?

    <p>Structural support</p> Signup and view all the answers

    Which of the following statements about cholesterol synthesis is accurate?

    <p>The liver is the primary site for cholesterol synthesis.</p> Signup and view all the answers

    What effect does ingesting cholesterol have on its synthesis in the body?

    <p>It leads to a decrease in cholesterol synthesis.</p> Signup and view all the answers

    Which type of food is known to contain high levels of cholesterol?

    <p>Animal products</p> Signup and view all the answers

    What is the primary function of lipoproteins in the body?

    <p>Transporting lipids</p> Signup and view all the answers

    Which of the following health conditions is NOT directly associated with cholesterol levels?

    <p>Liver cancer</p> Signup and view all the answers

    What percentage of body cholesterol is typically found in nerve and brain tissue?

    <p>10%</p> Signup and view all the answers

    What happens to cholesterol levels when it is consumed in the diet?

    <p>They can cause cardiovascular disease.</p> Signup and view all the answers

    Which statement correctly describes the density of lipoproteins?

    <p>Lipoproteins are less dense than ordinary protein molecules.</p> Signup and view all the answers

    How much cholesterol is synthesized by the liver each day?

    <p>800-1000 mg</p> Signup and view all the answers

    Which lipoprotein type has a density of less than 0.95 g/ml?

    <p>Chylomicrons</p> Signup and view all the answers

    Which component typically has the highest concentration in very low-density lipoproteins (VLDL)?

    <p>Triglycerides</p> Signup and view all the answers

    What enhances the hydrophilicity and solubility of bile acids?

    <p>Conjugation with amino acids</p> Signup and view all the answers

    Which major sterol is primarily found in plants?

    <p>Sitosterol</p> Signup and view all the answers

    What is the primary function of bile acids in the digestive system?

    <p>Emulsification of fats</p> Signup and view all the answers

    How are bile acids related to cholesterol?

    <p>Bile acids are synthesized from cholesterol.</p> Signup and view all the answers

    Which of the following is true regarding low-density lipoproteins (LDL)?

    <p>They have a density range of 1.006-1.063 g/ml.</p> Signup and view all the answers

    What is the primary component of biological membranes in eukaryotes?

    <p>Cholesterol</p> Signup and view all the answers

    What is a significant chemical characteristic of bile acids?

    <p>Multiple hydroxyl groups</p> Signup and view all the answers

    Which lipoprotein is associated with the transport of dietary lipids from the intestines?

    <p>Chylomicrons</p> Signup and view all the answers

    Study Notes

    Polyunsaturated Fatty Acids

    • More than one carbon-carbon double bond
    • Found in relatively minor amounts
    • Omega 6 and Omega 3 are common examples

    Common Polyunsaturated Fatty Acids

    • Linoleic acid: cis-9-, cis-12-octadecadienoic acid, 18 carbons, found in corn oil, animal tissues, bacteria
    • Linolenic acid: cis-9-, cis-12-, cis-15-octadecatrienoic acid, 18 carbons, found in animal tissues
    • Arachidonic acid: 5,8,11,14-eicosatetraenoic acid, 20 carbons, found in liver, brain tissue

    Trans Fatty Acids

    • Minor product of animal and plant metabolism
    • Produced synthetically by partial hydrogenation of fats and oils
    • Increase melting point of dietary fats
    • Favor freshness, give texture, improve stability

    Fatty Acid Characteristics

    • Melting point increases with increasing chain length
    • Even-numbered saturated fatty acids have higher melting points than odd-numbered ones
    • Increasing cis double bonds equals lower melting points
    • Longer chains are less soluble

    Space-Filling Molecules

    • Amount of bends in a fatty acid chain increases with the number of double bonds
    • Less packing occurs
    • Lower melting point
    • Tend to be liquids at room temperature

    Energy-Storage Materials

    • Triacylglycerols are the most widespread energy storage material in humans
    • Triacylglycerols are concentrated primarily in special cells (adipocytes)
    • Triacylglycerol hydrolysis is the reverse of esterification reaction
    • Lipase, an enzyme produced by the pancreas, carries out triacylglycerol hydrolysis within the human body

    Saponification

    • Hydrolysis in basic solution produces salt of fatty acid and glycerol
    • Most soap is prepared by hydrolyzing fats and oils under high pressure and temperature using sodium carbonate as a base

    Oxidation

    • Double bonds in triacylglycerols are subject to oxidation with oxygen in air
    • Oxidation of alkenes can result in two short-chain molecules - an aldehyde or carboxylic acid

    Rancidity

    • Occurs when fats and oils are exposed to air, moisture, light, bacteria, etc.
    • Hydrolytic rancidity occurs due to partial hydrolysis of triacylglycerol by bacterial enzymes

    Hydrogenation of a Triacylglycerol

    • Double bonds in unsaturated fatty acids react with hydrogen gas to produce carbon-carbon single bonds

    Waxes

    • Esters from long chain alcohol (fatty alcohol) and long chain carboxylic acid (fatty acid)
    • Hydrophobic: Waxes are water-repellent and do not dissolve in water
    • Solid at Room Temperature: Most waxes are solid at room temperatures.
    • Low Melting Point: Waxes generally have relatively low melting points

    Biological Membrane Lipids

    • Three main classes form the bilayer matrix of biological membranes: glycerophospholipids, sphingolipids, and sterols (principally cholesterol)

    Membrane Lipids: Phospholipids

    • Up to 80% of a cell membrane's mass can be lipid materials
    • Phospholipids dominate lipid materials in cell membranes
    • Functions of phospholipids:
      • Structural components of membranes.
      • Help in electron transport.
      • Absorb fat from the intestine.
      • Absorb fat from the liver and prevent fat accumulation in the liver.

    Triglycerides

    • Store fatty acids in biological systems
    • Almost all naturally occurring triglyceride molecules contain more than one type of fatty acid

    Properties of Triglycerides

    • Hydrophobic substances soluble only in some organic solvents
    • Neutral lipids with no electric charges
    • Melted triglycerides are generally quite viscous oils
    • Most stored triglycerides are fluid at body temperature to permit rapid mobilization as an energy source

    Types of Triacylglycerols

    • Simple triacylglycerols: three identical fatty acids are esterified
    • Mixed triacylglycerols: a triester formed from the esterification of glycerol with more than one kind of fatty acid

    Difference of Fats and Oils

    • Fats: Solids or semisolids at room temperature, primarily animal source, tasteless
    • Oils: Liquids at room temperature, primarily plant and fish oil source

    "Good Fats" versus "Bad Fats"

    • Type and amount offat are important for a balanced diet
    • Current recommended amounts
      • Total fat intake in calories: 15%
      • Monounsaturated fat: 10%
      • Polyunsaturated fat: 10%

    Chemical Reactions of Triacylglycerols

    • Ester and alkene functional groups determine chemical properties
    • Reactions:
      • Hydrolysis
      • Saponification
      • Hydrogenation

    Properties of Fatty Acids

    • Undergo esterification and acid-base reactions
    • Acidity does not vary greatly, indicated by pKa values
    • Solubility in water decreases as chain length increases
    • Exist as conjugate bases, like oleate, near neutral pH

    Fatty Acids: Saturated versus Unsaturated

    • Saturated fatty acids:
      • Bad cholesterol (low density lipoprotein)
      • Solid at room temperature
    • Unsaturated fatty acids:
      • Good cholesterol (high density lipoprotein)
      • Liquid at room temperature

    Saturated Fatty Acids

    • Unbranched, linear chains of CH2 groups with one terminal carboxylic acid group
    • The maximum possible number of hydrogen atoms are bonded to each carbon.
    • Common Saturated Fatty Acids:
      • Lauric acid: n-dodecanoic acid, 12 carbons, found in Palm kernel oil, nutmeg
      • Myristic acid: n-tetradecanoic acid, 14 carbons, found in Palm kernel oil, nutmeg
      • Palmitic acid: n-hexadecanoic acid, 16 carbons, found in Olive oil, animal lipids
      • Stearic acid: n-octadecanoic acid, 18 carbons, found in Cocoa butter, animal lipids

    Monounsaturated Fatty Acids

    • Dietary effect: Decrease in heart disease risk
    • Common Monounsaturated Fatty Acids:
      • Palmitoleic acid: cis-9-hexadecenoic acid, 16 carbons, found in Marine algae, pine oil
      • Oleic acid: cis-9-octadecenoic acid, 18 carbons, found in animal tissues, olive oil
      • Gadoleic acid: cis-9-eicosenoic acid, 20 carbons, found in fish oils (cod, sardine)

    Naming Monounsaturated Fatty Acids

    • Structural notation: Indicates the number of carbon atoms and the number of c-c double bonds present
      • e.g., 18:2 – 18 carbons, 2 double bonds
    • Delta notation: Specifies double-bond positioning within the carbon chain of an unsaturated fatty acid
      • Add Greek capital letter delta (∆) followed by one or more superscript numbers

    Leukotrienes

    • C20-fatty-acid derivative containing three conjugated double bonds and hydroxyl groups
    • Promote inflammatory and hypersensitivity (allergy) responses

    Clinical Significance: NSAIDs

    • Nonsteroidal anti-inflammatory drugs (NSAIDs): Inhibit COX enzymes, reducing the production of eicosanoids and relieving pain, inflammation, and fever.

    Clinical Significance: COX-2 Inhibitors

    • Selective inhibitors of COX-2 have been developed to reduce inflammation without the side effects associated with COX-1 inhibition.

    Polyunsaturated Fatty Acids

    • More than one carbon-carbon double bond
    • Cis in nature
    • Found in relatively minor amounts
    • Omega 6 and Omega 3 are examples

    Common Polyunsaturated Fatty Acids

    • Linoleic acid: cis-9-, cis-12-octadecadienoic acid
      • 18 carbons
      • Found in corn oil, animal tissues, bacteria
    • Linolenic acid: cis-9-, cis-12-, cis-15-octadecatrienoic acid
      • 18 carbons
      • Found in animal tissues
    • 5,8,11-eicosatrienoic acid
      • 20 carbons
    • 8,11,14-eicosatrienoic acid
      • 20 carbons
      • Found in brain tissue
    • 7,10,13-docosatrienoic acid
      • 22 carbons
      • Found in phospholipids
    • 8,11,14-docosatrienoic acid
      • 22 carbons
    • Arachidonic acid: 5,8,11,14-eicosatetraenoic acid
      • 20 carbons
      • Found in liver, brain tissue
    • 4,7,10,13-docosatetraenoic acid
      • 22 carbons
      • Found in brain tissue
    • 4,7,10,13,16,19-docosahexaenoic acid
      • 22 carbons
      • Found in brain tissue

    Trans Fatty Acids

    • Minor product of animal and plant metabolism
    • Produced synthetically by partial hydrogenation of fats and oils
    • Used in the manufacture of margarine
    • Increase melting point of dietary fats
    • Improve freshness, texture, stability

    Characteristics of Fatty Acids

    • Melting point increases with increasing chain length
    • Even-numbered saturated fatty acids have higher melting points than odd-numbered
    • Increase in cis double bonds = lower melting point
    • Longer the chain = less soluble it is

    Space-Filling Molecules

    • Number of bends in a fatty acid chain increase as the number of double bonds increase
    • Less packing occurs
    • Lower melting point
    • Tend to be liquids at room temperature

    Energy-Storage Materials

    • Essential for the synthesis of lipoproteins
    • Participate in blood

    Glycerophospholipids

    • Most abundant in biological membranes
    • Composed of a glycerol backbone, two fatty acid tails, and a phosphate head group

    Types of Glycerophospholipids

    • Phosphatidylcholine: one of the most common phospholipids in cell membranes
    • Phosphatidylethanolamine: another common phospholipid with a smaller head group
    • Phosphatidylserine: carries a negative charge and is often found in the inner leaflet of the membrane
    • Phosphatidylinositol: plays a role in cell signaling and membrane trafficking

    Phosphatidylcholine

    • Also known as lecithins
    • Waxy solids that form colloidal suspensions in water
    • Dietary sources: eggs yolk, soybeans
    • Within body: prevalent/present in cell membrane

    Sphingolipids

    • A second major class of lipids associated with the cell membrane
    • Based on an 18-carbon amine alcohol, sphingosine
    • Sphingomyelin: a molecule with a phosphorylcholine group instead of the sugar moiety
    • All sphingolipids have a fatty acid attached to the amino group of sphingosine
    • Only sphingomyelin, a phospholipid, is a major component of biological membranes

    Sphingoglycolipids

    • Contain a sugar attached to carbon 1 of sphingosine
    • Neutral glycosphingolipids: contain only neutral sugars and are found exclusively on the external surface of the cell membrane
      • Sugar moieties often act as antigens and as receptors for hormones and other signaling molecules
    • Occur primarily in brain (7% of dry mass)

    Gangliosides

    • Contain one or more sialic acid residues linked to the sugar
    • More complex form of sphingoglycolipid
    • Contains a branched chain of up to 7 monosaccharide residues
    • Gray matter of the brain

    Cerebrosides

    • The simplest form of sphingoglycolipids
    • Contain a single monosaccharide unit either glucose or galactose
    • Occur primarily in the brain
    • Also present in myelin sheath

    Cholesterol

    • Light yellow crystalline solid
    • Soluble in chloroform and other fat solvents
    • Polyunsaturated acids – lower the plasma cholesterol level
    • Most abundant lipid in the human body
    • Synthesized in the liver, adrenal cortex, intestines, testes and skin
    • Play an important role as a component of biomembranes and has a modulating effect on the fluid state

    Cholesterol Function

    • Important tissue component (modulating effect, integrity & permeability)
    • Play an important role in insulating nerves and brain structure
    • For transport of fatty acids in the body
    • It is a part of lipoproteins
    • Neutralizes the hemolytic action of various agents such as venom, bacterial toxins
    • Gives rise to “provitamin D”
    • It is a precursor of cholic acid in the body as also bile salts.
    • Micelle formation: Bile acids form mixed micelles with fatty acids, glycerol, and other lipids. These micelles transport lipids to the intestinal mucosa for absorption.
      • Absorption of lipids: Bile acids facilitate the absorption of dietary fats, fat-soluble vitamins (A, D, E, and K), and cholesterol from the small intestine.
      • Stimulation of bile flow: Bile acids can stimulate the secretion of more bile by the liver, enhancing fat digestion and absorption.

    Hormones

    • Biochemical substance produced by a ductless gland that has a messenger function.
    • Hormones serve as a means of communication between various tissues.
    • Some hormones are lipids.
    • Lipids that play the role of “chemical messengers” include:
      • Steroid hormones – derivatives of cholesterol
      • Eicosanoids- derivatives of arachidonic acid

    Steroid Hormones

    • Group of lipids that have fused-ring structure of 3 six-membered rings, and1 five-membered ring.

    Examples of Steroid Hormones

    • Progestins (active during pregnancy). Progesterone.
    • Glucocorticoids (promoting the synthesis of glucose and suppressing inflammatory reactions). Cortisol.
    • Mineralocorticoids (regulating ion balances). Aldosterone (Na+, K+, blood pressure).
    • Estrogens (promoting female sex characteristics). Estradiol.
    • Androgens (promoting male sex characteristics). Testosterone.

    Messenger Lipids: Eicosanoids

    • Arachidonic acid (20:4) derivatives:
      • Have profound physiological effects at extremely low concentrations.
      • Eicosanoids are hormone-like molecules.
      • Exert their effects in the tissues where they are synthesized.
      • Usually have a very short “life.”

    Prostaglandins

    • C20-fatty-acid derivative
    • Containing cyclopentane ring and oxygen-containing functional groups
    • Involved in:
      • Raising body temperature
      • Inhibiting the secretion of gastric juices
      • Increasing the secretion of a protective mucus layer into the stomach
      • Relaxing and contracting smooth muscle
      • Directing water and electrolyte balance
      • Intensifying pain
      • Enhancing inflammation responses

    Thromboxanes

    • C20-fatty-acid derivative
    • Containing a cyclic ether ring and oxygen-containing functional groups
    • Promote platelet aggregation.

    Leukotrienes

    • C20-fatty-acid derivative containing three conjugated double bonds and hydroxyl groups
    • Promote inflammatory and hypersensitivity (allergy) responses

    Clinical Significance

    • Nonsteroidal anti-inflammatory drugs (NSAIDs):

      • Inhibit COX enzymes, reducing the production of eicosanoids and relieving pain, inflammation, and fever.

    • COX-2 inhibitors:

      • Selective inhibitors of COX-2 have been developed to reduce inflammation without the side effects associated with COX-1 inhibition.

    Polyunsaturated Fatty Acids

    • Contain more than one carbon-carbon double bond
    • The double bond has a cis configuration
    • Found in relatively minor amounts
    • Omega 6 and Omega 3 are common examples
    • Linoleic acid (18 carbons) is found in corn oil, animal tissue and bacteria
    • Linolenic acid (18 carbons) is found in animal tissue
    • Arachidonic acid (20 carbons) is found in liver and brain tissue

    Trans Fatty Acids

    • Minor product of animal and plant metabolism
    • Produced synthetically during the partial hydrogenation of fats and oils
    • Most commonly used method to increase the melting point of dietary fats
    • Improves freshness, texture and stability

    Characteristics of Fatty Acids

    • Melting point increases with increasing chain length
    • Even-numbered saturated fatty acids have higher melting points than odd-numbered fatty acids.
    • Increasing cis double bonds lowers the melting point
    • Longer chain lengths lead to lower solubility

    Space-Filling Molecules

    • Amount of bends in a fatty acid chain increase with increasing number of double bonds
    • Less packing occurs because of these bends
    • This results in a lower melting point
    • Tends to be liquids at room temperature

    Energy-Storage Materials

    • Oxidation is the breakdown of molecules
    • Hydrolysis of triacylglycerol is the opposite of esterification
    • Breaks 1-2 ester bonds to generate mono- or diacylglycerol and fatty acids
    • In the human body, this is carried out by pancreatic enzymes called lipases

    Saponification

    • Hydrolysis of fats and oils in a basic solution
    • Produces salt of fatty acid and glycerol
    • Modern soap is prepared by hydrolyzing fats and oils with sodium carbonate under pressure and temperature
    • Coconut oil and animal fat are common sources

    Oxidation

    • Double bonds in triacylglycerols are susceptible to oxidation by oxygen in air
    • Leads to breaking of the carbon-carbon bond
    • Oxidation of alkenes can produce aldehydes or carboxylic acids

    Rancidity

    • Occurs when fats and oils are exposed to air, moisture, light, bacteria, etc.
    • Hydrolytic rancidity is caused by partial hydrolysis of triacylglycerol by bacterial enzymes

    Hydrogenation of a Triacylglycerol

    • Double bonds in unsaturated fatty acids react with hydrogen gas to produce carbon-carbon single bonds.
    • Unsaturated fatty acids can be converted to saturated fatty acids through hydrogenation

    Waxes

    • Esters created by long chain alcohols (fatty alcohols) and long chain carboxylic acids (fatty acids)
    • Hydrophobic, does not dissolve in water
    • Solid at room temperature
    • Have low melting points

    Biological Membrane Lipids

    • The bilayer matrix of biological membranes is comprised of glycerophospholipids, sphingolipids, and sterols (primarily cholesterol)

    Membrane Lipids: Phospholipids

    • All cells are surrounded by a membrane that confines their contents
    • Up to 80% of the mass of a cell membrane can be lipid materials, and these lipid materials are dominated by phospholipids
    • Structural components of membranes
    • Help in electron transport
    • Help absorb fat from the intestine
    • Help absorb fat from the liver and prevent fat accumulation in the liver
    • Contribute to the formation of sex hormones

    Functions of Cholesterol

    • Essential for many bodily processes, including:
      • Cell membranes
      • Nerve and brain tissue
      • Hormone synthesis
      • Vitamin production
    • Can lead to health problems if levels are too high, including:
      • Atherosclerosis
      • Diabetes mellitus
      • Hyperthyroidism
      • Xanthomatosis
      • Obstructive jaundice
      • Nephrotic Syndrome

    Cholesterol

    • Found in cell membranes, nerve tissue, and brain tissue
    • Important for the synthesis of hormones and vitamins
    • About 25% of cell membrane mass is cholesterol
    • About 10% of nerve and brain tissue dry mass is cholesterol
    • Typically 50mg of cholesterol is found in 100 ml of blood plasma, and around 170mg is esterified with fatty acids
    • Most cholesterol is biosynthesized by the liver and intestine
    • Approximately 800-1000mg of cholesterol is synthesized each day

    Cholesterol in Food

    • The liver synthesizes approximately 1 g of cholesterol per day
    • It is not necessary to consume cholesterol in diet
    • Cholesterol synthesis decreases if it is ingested
    • Animal food contains high amounts of cholesterol
    • Plant food does not contain cholesterol
    • If cholesterol intake is not reduced sufficiently, it can lead to cardiovascular disease

    Lipoproteins

    • Conjugated proteins involved in the transport and delivery of lipids to tissues
    • Carry lipids (cholesterol & triglycerides) along with water soluble carrier proteins
    • Transport neutral lipids in the blood
    • Have a lower density than ordinary protein molecules
    • Form micelles with bile acids, fatty acids, glycerol and other lipids
    • Micelles transport these lipids to the intestinal mucosa for absorption
    • Bile acids help absorb dietary fats, fat-soluble vitamins (A, D, E, and K) and cholesterol from the small intestine
    • Stimulates the liver to produce more bile, enhancing fat digestion and absorption

    Hormones

    • Biochemical messengers produced by ductless glands
    • Facilitate communication between tissues
    • Some hormones are lipids, including:
      • Steroid hormones (derived from cholesterol)
      • Eicosanoids (derivatives from arachidonic acid)

    Steroid Hormones

    • Lipids with a fused-ring structure of three six-membered rings, and one five-membered ring
    • Examples of steroid hormones include:
      • Progestins (active during pregnancy) - Progesterone
      • Glucocorticoids (promote glucose synthesis and suppress inflammation) - Cortisol
      • Mineralocorticoids (regulate ion balances) - Aldosterone (regulates sodium, potassium, and blood pressure)
      • Estrogens (promote female sex characteristics) - Estradiol
      • Androgens (promote male sex characteristics) - Testosterone

    Messenger Lipids: Eicosanoids

    • Derivatives of arachidonic acid (20:4)
    • Have profound physiological effects at extremely low concentrations
    • Hormone-like molecules that exert their effects in the tissues they are synthesized
    • Short lifespan

    Prostaglandins

    • C20-fatty acid derivative containing a cyclopentane ring and oxygen-containing functional groups
    • Functions include:
      • Raising body temperature
      • Inhibiting the secretion of gastric juices
      • Increasing the secretion of protective mucus in the stomach
      • Relaxing and contracting smooth muscle
      • Directing water and electrolyte balance
      • Intensifying pain
      • Enhancing inflammatory responses

    Thromboxanes

    • C20-fatty acid derivative containing a cyclic ether ring and oxygen-containing functional groups
    • Promote platelet aggregation

    Leukotrienes

    • C20-fatty acid derivative containing three conjugated double bonds and hydroxyl groups
    • Promote inflammatory and hypersensitivity (allergy) responses

    Clinical Significance

    • Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit COX enzymes, reducing the production of eicosanoids and relieving pain, inflammation, and fever
    • COX-2 inhibitors are selective inhibitors of COX-2 that reduce inflammation without the side effects associated with COX-1 inhibition.

    Lipids

    • Lipids are organic compounds found in living organisms that are insoluble in water but soluble in non-polar organic solvents.
    • Lipids do not have a common structural feature.

    Biological Significance of Fats

    • Lipids serve as energy storage, thermal insulation, metabolic fuels, membrane components, emulsifying agents in digestion and absorption of lipids, and precursors of vitamins A, C, D, E, and K.

    Chemical Composition of Fats

    • Most biological fatty acids contain an even number of carbon atoms.
    • The negatively charged carboxylate group of fatty acids is hydrophilic, while the rest of the molecule is hydrophobic.

    Physical Properties of Fats

    • The melting point of fatty acids increases with increasing chain length.
    • Even-numbered saturated fatty acids have higher melting points than odd-numbered ones.
    • Increase in cis double bonds reduces the melting point, while longer chains decrease solubility.

    Chemical Properties of Fats

    • Fatty acids undergo esterification and acid-base reactions.
    • The solubility of fatty acids in water decreases as chain length increases.
    • The even-numbered saturated fatty acids have higher melting points than the odd-numbered ones.
    • Increase in cis double bonds reduces the melting point, while longer chains decrease solubility.
    • The acidities of fatty acids do not vary greatly due to their pKa values.

    Classification of Lipids

    • Lipids can be classified into five categories: energy-storage lipids, membrane lipids, emulsification lipids, chemical messenger lipids, and protective-coating lipids.

    Fatty Acids

    • Most biological fatty acids contain an even number of carbon atoms.
    • They can be saturated or unsaturated, with saturated fatty acids linked by carbon-carbon single bonds, while unsaturated ones contain carbon-carbon double bonds.

    Saturated Fatty Acids

    • Saturated fatty acids are usually solid at room temperature.
    • They are associated with "bad cholesterol" (low-density lipoprotein).

    Unsaturated Fatty Acids

    • Unsaturated fatty acids are usually liquid at room temperature.
    • They are associated with "good cholesterol" (high-density lipoprotein).

    Monounsaturated Fatty Acids

    • Monounsaturated fatty acids have one double bond in their molecule and can reduce the risk of heart disease.

    Polyunsaturated Fatty Acids

    • Polyunsaturated fatty acids have more than one double bond and are essential for human health.
    • They are categorized into Omega 6 and Omega 3 fatty acids.

    Trans Fatty Acids

    • Trans fatty acids are produced synthetically by partial hydrogenation of fats and oils.
    • They are associated with an increased risk of heart disease.

    Triacylglycerols

    • Triacylglycerols are esters of glycerol with three fatty acids.
    • They are the main form of energy storage in animals and plants.
    • Hydrolysis of triacylglycerols breaks down the ester bonds, producing glycerol and fatty acids.
    • Saponification is the hydrolysis of triacylglycerols in a basic solution, producing salts of fatty acids and glycerol.

    Waxes

    • Waxes are esters of long-chain alcohols and long-chain fatty acids.
    • They are hydrophobic and solid at room temperature.
    • They have a low melting point.

    Membrane Lipids: Phospholipids

    • They are the main component of cell membranes.
    • They form a bilayer structure, with their hydrophilic heads facing outward and their hydrophobic tails facing inward.
    • Phospholipids play essential roles in cell signaling, cell growth, and membrane fluidity.

    Cholesterol

    • Cholesterol is a steroid, a type of lipid with a fused ring structure.
    • It is essential for cell membrane integrity and is a precursor for steroid hormones.
    • High levels of cholesterol in the blood can increase the risk of heart disease.

    Lipoproteins

    • Lipoproteins are complexes of lipids and proteins that transport lipids in the bloodstream.
    • Different types of lipoproteins have different densities and functions.

    Messenger Lipids

    • Messenger lipids, also known as signaling lipids, are involved in cell communication and regulation.
    • They include steroid hormones and eicosanoids.

    Steroid Hormones

    • Steroid hormones are synthesized from cholesterol.
    • They regulate a wide range of biological processes, including growth, development, and metabolism.
    • Examples of steroid hormones include estrogen, testosterone, cortisol, and aldosterone.

    Eicosanoids

    • Eicosanoids are synthesized from arachidonic acid.
    • They exert their effects locally in the tissues where they are synthesized.
    • They have a short lifespan and play critical roles in inflammation, pain, and blood clotting.
    • Examples of eicosanoids include prostaglandins, thromboxanes, and leukotrienes.

    Lipids

    • Lipids are organic compounds that are insoluble in water but soluble in non-polar organic solvents.
    • They are essential for life, playing important roles in energy storage, structure of membranes, hormonal function, and more.

    Composition of Lipids

    • Lipids are composed of carbon, hydrogen, and oxygen.
    • They can also contain other elements like phosphorus, nitrogen, and sulfur.

    Five Categories of Lipids

    • Energy-storage lipids: Triacylglycerols are the most common type of energy-storage lipids.
    • Membrane lipids: Phospholipids, sphingoglycolipids, and cholesterol are the main components of biological membranes.
    • Emulsification lipids: Bile acids are important for the digestion and absorption of fats.
    • Chemical messenger lipids: Steroid hormones and eicosanoids are chemical messengers produced by the body.
    • Protective-coating lipids: Biological waxes protect organisms from water and other environmental hazards.

    Functions of Lipids

    • Energy storage: Lipids provide a concentrated form of energy.
    • Thermal insulation: Lipids help to insulate the body and maintain body temperature.
    • Membrane components: Phospholipids and other lipids form the structural basis of cell membranes.
    • Hormones: Steroid hormones and eicosanoids play roles in regulating various bodily functions.
    • Vitamins: Vitamins A, D, E, and K are fat-soluble and require lipids for their absorption.
    • Surfactants: Lipids are used as surfactants in the lungs to reduce surface tension.
    • Nervous system: Lipids are essential for the structure and function of the nervous system.

    Classification of Lipids

    • Fatty acids: The building blocks of many lipids, fatty acids are long chains of hydrocarbons with a carboxyl group at one end. They can be saturated (no double bonds) or unsaturated (one or more double bonds).

    Saturated Fatty Acids

    • They are linear chains with no double bonds.
    • They are usually solid at room temperature and are associated with a higher risk of heart disease.
    • Examples: Lauric acid, Myristic acid, Palmitic acid, Stearic acid

    Monounsaturated Fatty Acids

    • They contain one double bond in their structure.
    • Usually liquid at room temperature and are associated with a lower risk of heart disease.
    • Examples: Palmitoleic acid, Oleic acid, Gadoleic acid, Erucic acid, Nervonic acid.

    Triacylglycerols

    • Formed by a glycerol molecule linked to three fatty acid molecules.
    • Major form of energy storage in animals.
    • Can be solid (fats) or liquid (oils) at room temperature depending on the type and amount of saturated and unsaturated fatty acids.

    Hydrolysis of Triacylglycerol

    • Breaking of the ester bonds in triacylglycerols, releasing glycerol and fatty acids.
    • This process is important for the digestion and absorption of fats.

    Saponification

    • Hydrolysis of triacylglycerols in basic solution, leading to the production of soap (salts of fatty acids) and glycerol.

    Oxidation of Lipids

    • Double bonds in unsaturated fatty acids can be oxidized by oxygen in the air, leading to rancidity (unpleasant taste and smell).

    Hydrogenation of Lipids

    • Unsaturated fatty acids can be converted to saturated fatty acids by adding hydrogen using catalysis.
    • This process is used in the production of margarine and other partially hydrogenated oils.

    Waxes

    • Esters formed between long-chain alcohols and long-chain fatty acids.
    • Hydrophobic and solid at room temperature, providing protective coatings for plants and animals.

    Biological Membrane Lipids

    • Glycerophospholipids: Contain a glycerol backbone, two fatty acid chains, and a phosphate group.
    • Sphingolipids: Contain a sphingosine backbone, one fatty acid chain, and a phosphate group.
    • Sterols: Steroids with a hydroxyl group, these lipids are important for maintaining the fluidity of membranes.

    Phospholipids

    • Key components of cell membranes, forming a bilayer structure with their hydrophilic heads facing the aqueous environment and hydrophobic tails facing inwards.
    • Play roles in electron transport, fat absorption, and micelle formation.

    Cholesterol

    • A sterol that plays a crucial role in cell membrane structure, hormone production, and vitamin D synthesis.
    • High levels of LDL cholesterol (bad cholesterol) are associated with a higher risk of heart disease.

    Hormones

    • Chemical messengers produced by the body to regulate various functions.
    • Some hormones are lipids, including steroid hormones and eicosanoids.

    Steroid Hormones

    • Derivatives of cholesterol.
    • Include: Progesterone, Cortisol, Aldosterone, Estradiol, Testosterone.
    • Each hormone has a specific function in the body, related to sexual development, metabolism, and other vital processes.

    Eicosanoids

    • Derivatives of arachidonic acid, a 20-carbon fatty acid.
    • Include: Prostaglandins, Thromboxanes, Leukotrienes.
    • These hormone-like molecules are involved in inflammation, blood clotting, pain sensation, and many other physiological processes.

    Prostaglandins

    • Involved in regulating a wide range of physiological functions, including raising body temperature, inhibiting gastric acid secretion, relaxing and contracting smooth muscles, and influencing pain and inflammation.

    Thromboxanes

    • Promote platelet aggregation, which is a key step in blood clotting.

    Leukotrienes

    • Contribute to inflammatory and hypersensitivity (allergy) responses.

    Clinical Significance

    • Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit COX enzymes, reducing eicosanoid production and relieving pain, inflammation, and fever.
    • COX-2 inhibitors are selective inhibitors of COX-2, aimed at reducing inflammation without the side effects associated with COX-1 inhibition.

    Lipids

    • Organic compounds found in living organisms.
    • Insoluble in water but soluble in non-polar organic solvents.
    • They do not have a common structural feature.

    Five Categories of Lipids

    • Energy storage lipids (triacylglycerols)
    • Membrane lipids (phospholipids, sphingoglycolipids, and cholesterol)
    • Emulsification Lipids (bile acids)
    • Chemical messenger lipids (steroid hormones and eicosanoids)
    • Protective coating lipids (biological waxes)

    Functions of Lipids

    • Energy storage (as triacylglycerol)
    • Thermal insulation
    • Membrane components
    • Emulsifying agents in digestion and absorption of lipids
    • Hormones (steroids and vitamin D metabolites)
    • Precursors of prostanoids and leukotrienes
    • Surfactants in the alveolar membrane
    • Participation in signal transduction pathways

    Classification of Lipids

    • Fatty acids
    • Triglycerides
    • Steroids

    Fatty Acids

    • Structural components of all lipids.
    • Most biological fatty acids contain an even number of carbon atoms.
    • The negatively charged carboxylate is hydrophilic.
    • Fatty acids undergo esterification and acid-base reactions.

    Saturated Fatty Acids

    • Unbranched, linear chains of CH2 groups linked by carbon-carbon single bonds with one terminal carboxylic acid group.
    • The maximum possible number of hydrogen atoms are bonded to each carbon of the molecule.

    Monounsaturated Fatty Acids

    • Dietary effect is a decrease in heart disease risk

    Triglycerides

    • Store fatty acids in biological systems.
    • Almost all naturally occurring triglyceride molecules contain more than one type of fatty acid.

    Two Types of Triacylglycerols

    • Simple triacylglycerols: Three identical fatty acids are esterified.
    • Mixed triacylglycerols: A triester formed from the esterification of glycerol with more than one kind of fatty acid.

    Difference of Fats and Oils

    • Fats: Solids or semisolids at room temperature, predominantly saturated, source - animal.
    • Oils: Predominantly liquids at room temperature, unsaturated, source - plant and fish oil.

    Glycerophospholipids

    • Most abundant in biological membranes.
    • They are composed of a glycerol backbone, two fatty acid tails, and a phosphate head group.

    Sphingolipids

    • A second major class of lipids associated with the cell membrane.
    • Are based on an 18-carbon amine alcohol, sphingosine.
    • All sphingolipids have, in addition to the sugar, a fatty acid attached to the amino group of sphingosine.

    Sphingomyelin

    • A phospholipid that is a major component of biological membranes.

    Gangliosides

    • Contain one or more sialic acid residues linked to the sugar.

    Leukotrienes

    • C20-fatty-acid derivative containing three conjugated double bonds and hydroxyl groups.
    • Promote inflammatory and hypersensitivity (allergy) responses.

    Clinical Significance

    • Nonsteroidal anti-inflammatory drugs (NSAIDs): Inhibit COX enzymes, reducing the production of eicosanoids and relieving pain, inflammation, and fever.
    • COX-2 inhibitors: Selective inhibitors of COX-2 have been developed to reduce inflammation without the side effects associated with COX-1 inhibition.

    Lipids

    • Lipids are organic compounds found in living organisms, insoluble in water but soluble in non-polar organic solvents.
    • Lipids do not have a common structural feature.

    Biological Significance of Fats

    • Lipids are essential for energy storage.
    • Thermal insulation provided by fats.
    • Fats are metabolic fuels.
    • Fats serve as membrane components.
    • Fats have emulsifying properties important in digestion and absorption.
    • Lipids are important in the synthesis of hormones, vitamins, and other metabolites.
    • Fats are surfactants in the alveolar membrane in the lungs.
    • Lipids participate in signal transduction pathways.
    • Fats are essential in cell wall and mitochondria constituents.
    • Lipids have an insulating effect.
    • Fats provide padding and protection to internal organs.
    • Fats are considered a source of fat-soluble vitamins A, D, E, and K.
    • Lipids are important for the nervous system.
    • Fats are a crucial source of essential fatty acids.

    Composition of Lipids

    • Lipids are primarily composed of carbon, hydrogen, and oxygen.
    • Some lipids also contain phosphorus, nitrogen, and sulfur.

    Types of Lipids

    • Five main categories of lipids:
      • Energy storage lipids: Triacylglycerols
      • Membrane lipids: Phospholipids, Sphingoglycolipids, and Cholesterol
      • Emulsification lipids: Bile acids
      • Chemical messenger lipids: Steroid hormones and Eicosanoids
      • Protective lipids: Biological waxes

    Fatty Acids

    • Fatty acids are the structural components of all lipids.
    • Most biological fatty acids contain an even number of carbon atoms.
    • Fatty acids are water-insoluble but have a hydrophilic carboxylate group.
    • Fatty acids undergo esterification and acid-base reactions.
    • The solubility of fatty acids in water decreases as the chain length increases.

    Fatty Acids: Saturated vs. Unsaturated

    • Saturated fatty acids:
      • Associated with "bad" cholesterol (LDL).
      • Solid at room temperature.
    • Unsaturated fatty acids:
      • Associated with "good" cholesterol (HDL).
      • Liquid at room temperature.

    Saturated Fatty Acids

    • Unbranched, linear chains of CH2 groups linked by carbon-carbon single bonds.
    • Have a terminal carboxylic acid group.
    • Contain the maximum possible number of hydrogen atoms bonded to each carbon.
    • Examples:
      • Lauric acid, Myristic acid, Palmitic acid, Stearic acid, Behenic acid, Lignoceric acid.

    Monounsaturated Fatty Acids

    • Contain one carbon-carbon double bond.
    • Associated with a decrease in heart disease risk.
    • Examples:
      • Palmitoleic acid, Oleic acid, Gadoleic acid, Erucic acid, Nervonic acid.

    Naming Monounsaturated Fatty Acids

    • Structural notation: indicates the number of carbon atoms and double bonds.
      • Example: 18:2 (18 carbons, 2 double bonds)
    • Delta (∆) notation: specifies the position of double bonds within the carbon chain.

    Functions of Cholesterol

    • Cholesterol is crucial for cell membranes, nerve tissue, and brain tissue.
    • Involved in the synthesis of hormones and vitamins essential for life.
    • Cholesterol is synthesized by the liver and intestine.
    • Cholesterol in food:
      • Liver synthesizes cholesterol, so dietary intake isn't essential.
      • Ingesting cholesterol can reduce synthesis but may lead to cardiovascular disease.
      • Animal foods are high in cholesterol, while plant foods contain no cholesterol.

    Lipoproteins

    • Conjugated proteins responsible for transporting and delivering lipids to tissues.
    • Transport neutral lipids in the blood.
    • Have a lower density than ordinary protein molecules.

    Lipoprotein Classes Based on Density

    • Chylomicrons: Highest lipid content, lowest density.
    • Very-low-density lipoproteins (VLDL): High triglyceride content.
    • Low-density lipoproteins (LDL): Primarily carry cholesterol.
    • High-density lipoproteins (HDL): High protein content, "good" cholesterol.

    Distribution of Lipoproteins in Body Tissues

    • Lipids are distributed across various tissues like the nucleus, cell membranes, plasma, etc.

    Sterols

    • Major components of biological membranes in eukaryotes.
    • Cholesterol is the primary sterol in animals, while ergosterol is the main sterol in fungi and sitosterol in plants.

    Bile Acids

    • Derived from cholesterol.
    • Increase hydrophilicity and solubility in water.
    • Often conjugated with glycine or taurine to enhance solubility and neutralization.
    • Functions:
      • Emulsification: breaks down fat droplets into micelles.
      • Micelle formation: transports lipids to the intestinal mucosa.
      • Absorption of lipids: facilitates absorption of dietary fats, fat-soluble vitamins, and cholesterol.
      • Stimulates bile flow: enhances fat digestion and absorption.

    Hormones

    • Biochemical messengers produced by ductless glands.
    • Some hormones are lipids.
    • Lipid hormones:
      • Steroid hormones: Derivatives of cholesterol.
      • Eicosanoids: Derivatives of arachidonic acid.

    Steroid Hormones

    • Have a fused-ring structure: 3 six-membered rings, 1 five-membered ring.
    • Examples:
      • Progestins: Active during pregnancy.
      • Glucocorticoids: Promote glucose synthesis, suppress inflammation.
      • Mineralocorticoids: Regulate ion balance, blood pressure.
      • Estrogens: Promote female characteristics.
      • Androgens: Promote male characteristics.

    Messenger Lipids: Eicosanoids

    • Derivatives of arachidonic acid (20:4).
    • Have profound physiological effects at low concentrations.
    • Function as hormone-like molecules that act locally.
    • Generally have a short lifespan.

    Prostaglandins

    • 20-carbon fatty acid derivatives containing a cyclopentane ring.
    • Involved in:
      • Raising body temperature.
      • Inhibiting gastric juice secretion.
      • Increasing protective mucus production in the stomach.
      • Relaxing and contracting smooth muscles.
      • Regulating water and electrolyte balance.
      • Intensifying pain.
      • Enhancing inflammation responses.

    Thromboxanes

    • 20-carbon fatty acid derivatives containing a cyclic ether ring.
    • Promote platelet aggregation.

    Polyunsaturated Fatty Acids

    • Have more than one carbon-carbon double bond
    • Occur naturally in cis conformation
    • Found in relatively small amounts
    • Omega 6 and Omega 3 are two examples
    • Linoleic acid is a common example with 18 carbons
    • Arachidonic acid has 20 carbons which are found in liver and brain tissue

    Trans Fatty Acids

    • Minor products of animal and plant metabolism
    • Produced synthetically by partial hydrogenation of fats and oils during the manufacture of margarine
    • Used to increase melting point of dietary fats, improve freshness, texture, and stability

    Characteristics of Fatty Acids

    • The melting point of fatty acids increases with increasing chain length
    • The even-numbered saturated fatty acids have a higher melting point than the odd-numbered
    • Increase in cis double bonds decreases melting point
    • Longer chains are less soluble

    Space-Filling Molecules

    • The amount of bends in a fatty acid chain increases as the number of double bonds increases
    • This leads to less packing and a lower melting point
    • They tend to be liquids at room temperature

    Energy Storage Materials

    • Human cells store small amounts of energy-providing materials, except for nerve cells
    • Carbohydrate glycogen is the most widespread energy storage material present in small amounts
    • The storage material is triacylglycerols
    • Triacylglycerols are concentrated primarily in special cells called adipocytes

    Triglycerides

    • Nearly all naturally occurring triglyceride molecules contain more than one type of fatty acid
    • Almost all naturally occurring triglyceride molecules contain more than one type of fatty acid.

    Properties of Triglycerides

    • Hydrophobic substances that are soluble in some organic solvents
    • Possess no electrical charges which makes them neutral lipids
    • Melted triglycerides are generally quite viscous oils
    • Most stored triglycerides are fluid at body temperature to permit their rapid mobilization as an energy source

    Two Types of Triacylglycerols

    • Simple triacylglycerols: three identical fatty acids are esterified
    • Mixed triacylglycerols: a triester formed from the esterification of glycerol with more than one kind of fatty acid

    Difference Between Fats and Oils

    • Fats are solids or semisolid at room temperature
    • Fats are primarily sourced from animals
    • Oils are liquids at room temperature
    • Oils are primarily sourced from plants and fish oil

    "Good Fats" Versus "Bad Fats"

    • Studies indicate that the type of dietary fat and the amount of dietary fat are important for a balanced diet
    • Current recommended amounts are: total fat intake in calories: 15% - monounsaturated fat 10% - polyunsaturated

    Chemical Reactions of Triacylglycerols

    • Two functional groups: esters and alkenes
    • Hydrolysis and saponification are two chemical reactions

    Functions of Cholesterol

    • Important in human cell membranes, nerve tissue and brain tissue
    • Important in chemical synthesis: hormones, vitamins essential for life
      • Cell membranes: 25% by mass
      • Nerve and brain tissue: 10% by dry mass
      • Blood plasma (every 100 ml): 50 mg and about 170 mg of cholesterol esterified with various fatty acids
      • Most cholesterol is biosynthesized by the liver and the intestine
      • About 800-1000 mg each day are synthesized

    Cholesterol in Food

    • Liver synthesizes cholesterol: ~ 1g everyday
    • Cholesterol is not necessary to consume in the form of diet
    • Cholesterol synthesis decreases if it is ingested
    • Reduction is not sufficient and can lead to cardiovascular disease
      • Animal food: lot of cholesterol
      • Plant food: no cholesterol

    Lipoproteins

    • Conjugated proteins involved in transport and delivery of lipids to tissues.
    • Examples: Lipids (Cholesterol & triglycerides) + water-soluble carrier proteins
    • Transport neutral lipids in the blood
    • Lower density than ordinary protein molecules

    Lipoproteins According to Density

    • The density of a lipoprotein can be used to classify it, with differences in the amount of protein, triglycerides, cholesterol, and phospholipids present.

    Distribution of Lipoproteins in Body Tissues

    • Lipoproteins are present in different locations in the body, including the nucleus, cell membranes, plasma, and more.

    Sterols

    • Major components of biological membranes in eukaryotes but are rare in prokaryotes
    • Cholesterol is the principal sterol in animals, whereas the major sterol in fungi is ergosterol and that in plants is sitosterol

    Structure of Bile Acids

    • Derived from cholesterol (steroid lipid)
    • Contain multiple hydroxyl groups that increase hydrophilicity and solubility in water
    • Conjugated with glycine or taurine to further increase their solubility and neutralize acidic properties

    Function of Bile Acids

    • Emulsification: reduce the surface tension of fat droplets, breaking them down into smaller micelles. This increases the surface area for digestion
    • Micelle formation: form mixed micelles with fatty acids, glycerol, and other lipids, transporting lipids to the intestinal mucosa for absorption
    • Absorption of lipids: facilitate the absorption of dietary fats, fat-soluble vitamins, and cholesterol from the small intestine
    • Stimulation of bile flow: stimulate the secretion of more bile by the liver, enhancing fat digestion and absorption

    Hormones

    • Biochemical substances produced by a ductless gland that have a messenger function
    • Serve as a means of communication between various tissues
    • Some hormones are lipids, including steroid hormones and eicosanoids.

    Steroid Hormones

    • Group of lipids with a fused-ring structure of 3 six-membered rings, and 1 five-membered ring.

    Examples of Steroid Hormones

    • Progestins (active during pregnancy)
    • Glucocorticoids (promote glucose synthesis and suppress inflammation)
    • Mineralocorticoids (regulate ion balance)
    • Estrogens (promote female sex characteristics)
    • Androgens (promote male sex characteristics)

    Messenger Lipids: Eicosanoids

    • Derived from arachidonic acid (20:4)
    • Have profound physiological effects at extremely low concentrations.
    • Eicosanoids are hormone-like molecules
    • Exert their effects in the tissues where they are synthesized
    • Eicosanoids usually have a very short “life.”

    Prostaglandins

    • C20-fatty-acid derivative containing a cyclopentane ring and oxygen-containing functional groups
    • Involved in raising body temperature, inhibiting gastric juice secretion, increasing protective mucus secretion in the stomach, relaxing and contracting smooth muscle, directing water and electrolyte balance, intensifying pain, and enhancing inflammation responses.

    Thromboxanes

    • C20-fatty-acid derivative containing a cyclic ether ring and oxygen-containing functional groups
    • Promote platelet aggregation.

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    Week 8 - Lipids PDF

    Description

    Explore the fascinating world of fatty acids, focusing on polyunsaturated and trans fatty acids. This quiz covers key characteristics, sources, and examples of important fatty acids like linoleic and arachidonic acids. Test your knowledge and understanding of fatty acid structures and properties.

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