Biochemistry of Lipids
29 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following is NOT a function of lipids in the body?

  • Transporting oxygen through the bloodstream (correct)
  • Cushioning internal organs
  • Acting as a component of cell membranes
  • Providing energy as a reservoir
  • Which of the following is a characteristic of lipids, as defined in the text?

  • Insoluble in organic solvents
  • Soluble in water
  • Usually composed of carbohydrates and nitrogen
  • Relatively insoluble in water (correct)
  • What is the primary chemical linkage involved in the formation of lipids?

  • Ester bonds (correct)
  • Peptide bonds
  • Hydrogen bonds
  • Glycosidic bonds
  • What is the approximate caloric value of lipids, per gram?

    <p>9 kcal/g (C)</p> Signup and view all the answers

    Which of the following lipids contribute to the structure of cell membranes?

    <p>Phospholipids (C)</p> Signup and view all the answers

    Which of the following is NOT a disease directly associated with abnormal lipid metabolism?

    <p>Influenza (D)</p> Signup and view all the answers

    What is the primary function of the myelin sheath?

    <p>Provide insulation for nerve cells (C)</p> Signup and view all the answers

    Which of the following is NOT a type of lipid found in the classification outlined in the text?

    <p>Glycoproteins (B)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of unsaturated fatty acids (UFA)?

    <p>Have a higher melting point than saturated fatty acids (SFA). (A)</p> Signup and view all the answers

    What is the main form of fat stored in the body?

    <p>Triglycerides (C)</p> Signup and view all the answers

    Which of the following is NOT a source of triglycerides in the body?

    <p>Muscle tissue (A)</p> Signup and view all the answers

    What type of reaction occurs when a fatty acid combines with glycerol to form a triglyceride?

    <p>Esterification (A)</p> Signup and view all the answers

    Which statement regarding the structure of a triglyceride is TRUE?

    <p>Triglycerides are composed of one glycerol molecule and three fatty acids. (D)</p> Signup and view all the answers

    What is the general structural formula for a fatty acid?

    <p>R-COOH (D)</p> Signup and view all the answers

    What is the main reason for the increase in melting point of fatty acids as their chain length increases?

    <p>Increased number of carbon atoms leading to stronger intermolecular forces (A)</p> Signup and view all the answers

    What is the primary reason for the rancidity in unsaturated fatty acids?

    <p>Oxidation of the carbon chain (C)</p> Signup and view all the answers

    What is the primary disadvantage of partially hydrogenating fats?

    <p>It can lead to the formation of trans fats, potentially increasing LDL cholesterol and the risk of heart disease. (C)</p> Signup and view all the answers

    What is the impact of trans fats on LDL receptor activity?

    <p>Trans fats decrease LDL receptor activity, leading to an increase in LDL cholesterol levels. (A)</p> Signup and view all the answers

    What is the main difference between cis and trans fats?

    <p>Cis fats have hydrogen atoms on the same side of the double bond, while trans fats have them on opposite sides. (A)</p> Signup and view all the answers

    Which of the following is NOT a recommended strategy for reducing fat intake?

    <p>Using butter instead of margarine or other spreads. (B)</p> Signup and view all the answers

    What is the recommended daily intake of fat?

    <p>The recommended intake varies depending on age, gender, and activity level. (A)</p> Signup and view all the answers

    Which of the following acids is NOT a saturated fatty acid?

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

    What is the general formula for saturated fatty acids?

    <p>CH3-(CH2)n-COOH (B)</p> Signup and view all the answers

    Which of the following statements is TRUE about unsaturated fatty acids?

    <p>They contain at least one double bond between carbon atoms. (C)</p> Signup and view all the answers

    What is the difference between omega-3 and omega-6 fatty acids?

    <p>The location of the double bond closest to the methyl (CH3) end. (A)</p> Signup and view all the answers

    Which of the following fatty acids is considered essential?

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

    What is the primary effect of hydrogenation on polyunsaturated fatty acids?

    <p>Decreases their number of double bonds. (B), Increases their melting point. (D)</p> Signup and view all the answers

    What is the main function of essential fatty acids in the body?

    <p>Act as building blocks for cell membranes. (A)</p> Signup and view all the answers

    Which of the following is NOT a function of omega-3 fatty acids?

    <p>Increasing inflammation. (B)</p> Signup and view all the answers

    Flashcards

    Saturated Fatty Acids (SFA)

    Fatty acids without double bonds, solid at room temperature, with a general formula of CH3-(CH2)n-COOH.

    Examples of Saturated FAs

    Common saturated fatty acids include acetic, butyric, palmitic, and stearic acids.

    Unsaturated Fatty Acids (UFA)

    Fatty acids with one or more double bonds, usually liquid at room temperature.

    Cis vs Trans Isomers

    Unsaturated fatty acids include natural cis isomers and may form trans isomers during metabolism.

    Signup and view all the flashcards

    Omega-3 Fatty Acids

    Essential fatty acids known for lowering blood pressure and reducing clotting risks.

    Signup and view all the flashcards

    Essential Fatty Acids

    Fatty acids like linolenic and linoleic that cannot be synthesized by the body.

    Signup and view all the flashcards

    Role of Eicosanoids

    Hormone-like chemicals derived from fatty acids regulating functions like blood pressure.

    Signup and view all the flashcards

    Hydrogenation of PUFAs

    A process that makes polyunsaturated fats more stable and resistant to oxidation.

    Signup and view all the flashcards

    Lipids

    Heterogeneous organic substances that are hydrophobic and soluble in organic solvents.

    Signup and view all the flashcards

    Functions of Lipids

    Roles include energy reservoir, cell membrane constituents, insulation, and protection.

    Signup and view all the flashcards

    Triglycerides

    Primary form of stored energy in the body, yielding 9 Kcal/g.

    Signup and view all the flashcards

    Phospholipids

    Key component of cell membranes, consisting of a glycerol, two fatty acids, and a phosphate group.

    Signup and view all the flashcards

    Sterols

    A type of lipid that includes cholesterol, important for cell membrane stability and hormone production.

    Signup and view all the flashcards

    Clinical Significance of Lipids

    Understanding lipid metabolism disorders like obesity, atherosclerosis, and diabetes mellitus.

    Signup and view all the flashcards

    Simple Lipids

    Include triglycerides and waxes, composed of fatty acids and alcohols.

    Signup and view all the flashcards

    Compound Lipids

    Include phospholipids and glycolipids; complex structures with functional groups.

    Signup and view all the flashcards

    Trans Fats

    Unsaturated fats that have been partially hydrogenated, altering their structure.

    Signup and view all the flashcards

    Cis Fats

    Natural unsaturated fats where hydrogen atoms are on the same side of the double bond.

    Signup and view all the flashcards

    LDL-C

    Low-Density Lipoprotein Cholesterol, often referred to as 'bad cholesterol'.

    Signup and view all the flashcards

    Moderation in Fat Use

    Advising limited intake of fats to maintain health.

    Signup and view all the flashcards

    Hidden Fats

    Fats that are not obvious in processed or convenience foods.

    Signup and view all the flashcards

    Glycolipids

    Lipids with sugar moieties, important for cell recognition.

    Signup and view all the flashcards

    Fatty Acids

    Carboxylic acids with long hydrocarbon chains, key lipid components.

    Signup and view all the flashcards

    Saturated Fatty Acids

    Fatty acids with all carbon bonds filled with hydrogen, no double bonds.

    Signup and view all the flashcards

    Unsaturated Fatty Acids

    Fatty acids with one or more double bonds between carbons.

    Signup and view all the flashcards

    Ester Formation

    Reaction between fatty acids and alcohol, producing esters like triglycerides.

    Signup and view all the flashcards

    Hydrogenation

    Process converting unsaturated fatty acids to saturated forms by adding hydrogen.

    Signup and view all the flashcards

    Study Notes

    Lipids Chemistry

    • Lipids are heterogeneous organic substances relatively insoluble in water (hydrophobic) but soluble in organic solvents.
    • Lipids consist of alcohol and fatty acids joined by ester linkage.
    • Lipids have multiple functions:
      • Reservoir for energy (e.g., triglycerides, 9 Kcal/g, 60% of body's energy).
      • Cell membrane constituents (e.g., phospholipids, cholesterol).
      • Insulators on neurons (e.g., myelin sheath).
      • Protecting internal organs.
      • Providing shape and contour to the body.
      • Acting as emulsifiers, detergents, and emulsifying agents (e.g., lecithin, sphingomyelin, bile acid).
      • Regulating metabolic processes (e.g., steroid hormones, prostaglandins).
      • Contributing to food flavor, aroma, and palatability.
      • Protection against external heat changes.
      • Absorption of fat-soluble vitamins.
    • Clinical significance of abnormal lipid metabolism includes:
      • Obesity
      • Atherosclerosis
      • Hyperlipidemia/hypercholesterolemia
      • Diabetes mellitus
      • Fatty liver
      • Lipid storage diseases (e.g., Gauchers, Niemann-Pick, Fabry's, and Tay-Sach's diseases).

    Classification of Lipids

    • Simple lipids: esters of fatty acids with alcohols (e.g., triglycerides & waxes).
    • Compound lipids: esters of fatty acids with alcohols and functional groups (e.g., phospholipids, glycolipids).
    • Derived lipids: steroids, cholesterol, PGs, and leukotrienes.

    Simple and Compound Lipids

    • Simple lipids:
      • Triacylglycerol/triglycerides/neutral fats
      • Waxes: esters of FA with alcohol
    • Compound lipids:
      • Phospholipids:
        • Nitrogen-containing phospholipids: lecithin, cephalin, phosphatidyl serine
        • Non-nitrogen-containing phospholipids: phosphatidyl inositol, phosphatidyl glycerol, cardiolipin (diphosphatidyl glycerol)
      • Plasmalogens: lipids with long chain alcohol (e.g. choline & ethanolamine).
      • Sphingomyelin
      • Glycolipids: (e.g. cerebrosides, globosides, gangliosides)
      • Sulpholipids: (e.g. Sulphated glycolipids)

    Derived Lipids

    • Steroids (e.g., cholesterol, prostaglandins, leukotrienes, terpenes)
    • Lipids conjugated with other compounds (e.g., lipoproteins, glycolipids).

    Examples of Lipids

    • Triglycerides
    • Phospholipids
    • Steroids (cholesterol)

    Triglycerides

    • Esters of fatty acids with alcohol
    • Predominant form of fat in food and major fuel store in the body (90% of dietary intake).
    • Composed of 3 fatty acids + glycerol.
    • Triglyceride structure formation involves condensation reactions.

    Fatty Acids

    • Organic acids with chains of carbons, hydrogen, and an acid group at one end and a methyl group at the other end.
    • Exist as esters on different classes of lipids.
    • In humans, FFAs are formed only during metabolism.
    • General structure is R--COOH

    Properties of FA

    • Hydrogenation: Unsaturated FAs can be converted to saturated FAs.
    • Halogenation: Unsaturated FAs react with halogens.
    • Melting point: Increases with increased chain length
    • Short/medium-chain FAs have lower melting points than long-chain FAs.
    • Salt formation: FAs and SFA can form salts (soaps) with Na, K, Ca, or Mg.
    • Ester formation: UFA & SFA react with alcohol (e.g., glycerol) to form esters: glycerol+FA=monoacylglycerol; monoacylglycerol+FA=diacylglycerol; diacylglycerol+FA=triacylglycerol.
    • Oxidation: FAs can oxidize forming energy in beta-oxidation.

    Classifications of Fatty Acids (FAs)

    • Depending on the total number of carbon atoms: Even-chain FAs (C2, C4, …) vs. Odd-chain FAs (C3, C5, …).
    • Depending on the length of hydrocarbon chain: Short-chain (C2-C6), medium-chain (C8-C14), long-chain (C16-C22), very long-chain (>C24).
    • Depending on the nature of the hydrocarbon chain:
      • Saturated FAs (no double bonds): (e.g., acetic, butyric, palmitic, stearic, arachidic acids).
      • Unsaturated FAs (one or more double bonds):
        • Mono-unsaturated (one double bond) (e.g., palmitoleic, oleic).
        • Poly-unsaturated (more than one double bond) (e.g., linoleic, α-linolenic, arachidonic).
      • Branched-chain FAs
      • Hydroxy FAs

    Common Fatty Acids and Their Characteristics

    • Lists various FAs (even-chain, saturated and unsaturated).
    • Includes examples of food sources.

    Unsaturated Fatty Acids (UFAs)

    • Contain double bonds (C=C).
    • Usually liquids at room temperature, becoming more fluid with increased C=C bonds.
    • Naturally exist primarily as cis-isomers, but trans-isomers may form during metabolism.
    • Types: MUFA (e.g., oleic acid) and PUFA (e.g., linoleic acid, linolenic acid, arachidonic acid), omega-3 and omega-6

    Omega-3 and Omega-6 Fatty Acids

    • Omega numbering refers to the location of the first double bond from the methyl end of the carbon chain.
    • Essential fatty acids (EFAs) cannot be synthesized by the body and must be obtained from the diet. Omega-3 and omega-6 are essential fatty acids.

    Essential Fatty Acids

    • Linoleic and linolenic acids are essential because the body cannot synthesize them.
    • Arachidonic acid is semi-essential, becoming essential when its precursor (linoleic/omega-6) is not provided.
    • Functions of EFAs include:
      • Cell membrane components.
      • Eicosanoid synthesis (hormone-like chemicals).

    Sources of Omega Fatty Acids

    • Tables listing common food sources of omega-6 and omega-3 fatty acids including vegetable oils, nuts, seeds, meats, poultry, eggs, fish, etc.

    Hydrogenation of PUFA

    • Hydrogenation of UFAs creates more chemically stable fats with increased food shelf life, useful in food processing (margarine, peanut butter, baked goods).
    • The downside is the creation of trans fats leading to health issues.

    Cis vs Trans Fats

    • Cis fats have hydrogens on the same side of the double bond and typically appear more bent
    • Trans fats have hydrogens on the opposite side of the bond and are straighter or linear in form.

    Major Sources of Various Fatty Acids

    • Tables listing healthy fats with their sources.

    Harmful Fatty Acids

    • Lists common sources of saturated and trans fats.

    Phospholipids

    • Specialized form of compound lipids consisting of fatty acids, glycerol, and phosphorylated nitrogen bases (e.g., serine, ethanolamine, choline, inositol, sphingosine).
    • Amphipathic nature allows for formation of lipid bilayers.
    • Types include phosphoglycerides (e.g., phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol, cardiolipin), phosphoinositides, and phosphosphingosides (e.g., sphingomyelin).

    Phosphoglycerides

    • Major phospholipids in cell membranes.
    • Contain two fatty acids esterified to the first and second hydroxyl groups of glycerol (1st and 2nd OH groups).
    • The third hydroxyl group (OH) forms an ester bond with phosphate.
    • Subtypes: lecithin, cephalins, plasmalogen

    Plasmalogens

    • Structurally related to lecithins and cephalins, differing in one of the fatty acids which is replaced by an unsaturated alkyl ether linkage.
    • Found in brain and muscle tissue.

    Phosphoinositides

    • Phosphatidylinositol (PI)
    • Involves inositol as part of the structure instead of ethanolamine or choline.

    Phosphosphingosides (sphingomyelins)

    • Backbones of sphingomyelin is sphingosine, not glycerol.
    • Fatty acids common in sphingomyelin include palmitic, stearic, lignoceric, and nervonic acid.
    • Important constituent of myelin sheaths in nerve fibers.

    Glycolipids

    • Contain both carbohydrate and lipid components.
    • Derivatives of ceramides (long-chain fatty acid attached to sphingosine)
    • Types: cerebrosides, gangliosides, and acidic glycosphingolipids (e.g., sulfatides).

    Cerebrosides

    • Simplest type of neutral glycosphingolipid, consisting of one or more carbohydrate units (e.g., galactose or glucose).
    • Important constituent of brain tissue.
    • Deficiency of glucocerebrosidase results in Gaucher's disease.

    Gangliosides

    • Contain complex carbohydrate units and sialic acid (N-acetylneuraminic acid).
    • Important constituent of membrane lipids in brain tissue.
    • Act as receptors for pathogens.

    Structure of Glycosphingolipids

    • Glycosphingo lipids differ from sphingomyelin as they do not contain phosphate, using a monosaccharide or oligosaccharide attached to the ceramide in an O-glycosidic bond instead of a phosphate group

    Sterols

    • Lipids possessing multiple cyclic carbon rings, including cholesterol, Vitamin D, Sex hormones, and bile acids.

    Cholesterol

    • A crucial sterol.
    • It is synthesized by the liver among other tissues, making it an endogenous source.
    • Important component of cell membranes affecting fluidity and permeability.
    • Precursor to steroid hormones, bile acids, and Vitamin D.

    Sources of Cholesterol

    • Includes endogenous sources (liver, adrenal cortex, gonads, skin, and intestine) and exogenous sources (diet).

    Functions of Cholesterol

    • Important membrane component influencing fluidity and permeability
    • Precursor to steroids (steroid hormones, bile acids, Vitamin D)

    Lipoproteins

    • Transport hydrophobic lipids in the bloodstream.
    • Types include HDL, LDL, VLDL, and chylomicrons.
    • Each type has a specific density, diameter, protein composition, and lipid content.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Lipids Note 1 PDF

    Description

    Test your knowledge on the functions, characteristics, and structures of lipids in the body. This quiz covers key topics including lipid metabolism, triglycerides, and the role of lipids in cellular structures. Perfect for students studying biochemistry or related fields.

    More Like This

    Biochemistry Chapter on Lipids
    48 questions

    Biochemistry Chapter on Lipids

    BestPerformingAntigorite4922 avatar
    BestPerformingAntigorite4922
    Biochemistry: Lipids and Membranes
    48 questions

    Biochemistry: Lipids and Membranes

    BestPerformingAntigorite4922 avatar
    BestPerformingAntigorite4922
    Lipids: Classification and Structure
    5 questions
    Use Quizgecko on...
    Browser
    Browser