Nutrition Lipids and Fatty Acids Quiz
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Questions and Answers

Which type of lipid primarily makes up the majority of nutritional lipids?

  • Fats and oils (correct)
  • Phospholipids
  • Steroids
  • Waxes

What characteristic distinguishes saturated fatty acids from unsaturated fatty acids?

  • Solubility in water
  • Presence of multiple double bonds
  • Presence of single bonds (correct)
  • Long hydrocarbon chains

Why do saturated fatty acids typically have high melting points?

  • Their molecules fit closely together in a regular pattern. (correct)
  • They form fewer dispersion forces.
  • They contain polar groups.
  • They dissolve well in water.

What type of fatty acid contains only one double bond?

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

Which of the following statements about lipids is incorrect?

<p>Waxes are primarily used for storage. (A)</p> Signup and view all the answers

What is produced in small amounts in the stomachs of ruminating animals?

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

Which of the following statements about cholesterol is true?

<p>It serves as a steroidal alcohol. (A)</p> Signup and view all the answers

How is cholesterol transported in the bloodstream?

<p>Encased in a protein sheath (B)</p> Signup and view all the answers

Which of the following options contributes to higher cholesterol levels?

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

What is a characteristic of trans fats compared to cis fats?

<p>They are considered unnatural and 'bad'. (B)</p> Signup and view all the answers

What type of fats are solid at room temperature?

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

Which of the following fatty acids is considered essential for humans?

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

What process is used to convert unsaturated fats into saturated fats?

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

What is the result of saponification of a triglyceride?

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

Which fatty acid is primarily found in fish oils and has a polyunsaturated structure?

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

Cis and trans fatty acids differ in what way?

<p>Stereochemistry of double bonds (D)</p> Signup and view all the answers

What term is used to describe fatty acids that cannot be synthesized by the human body?

<p>Essential fatty acids (B)</p> Signup and view all the answers

Which of the following oils is typically liquid at room temperature?

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

What is the characteristic behavior of whale oil at different depths while swimming?

<p>It increases in density when solidified at greater depths. (B)</p> Signup and view all the answers

Which statement about soaps and detergents is correct?

<p>Detergents contain a hydrocarbon tail and a charged head. (B)</p> Signup and view all the answers

Why is water at 4°C considered the most dense?

<p>Due to the unique bonding arrangement of water molecules. (B)</p> Signup and view all the answers

What causes curd formation in soaps when used in hard water?

<p>Insoluble carboxylates from metal ions like Fe, Ca, and Mg. (D)</p> Signup and view all the answers

What property of ice makes it unique compared to most substances?

<p>Ice is less dense than liquid water. (D)</p> Signup and view all the answers

What structural feature distinguishes unsaturated fatty acids from saturated fatty acids?

<p>Unsaturated fatty acids contain double bonds in their chains. (B)</p> Signup and view all the answers

Which of the following fatty acids has the highest melting point?

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

What characterizes triacylglycerols?

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

Why do unsaturated fatty acids generally have lower melting points than saturated fatty acids?

<p>Their nonlinear chains prevent close packing. (B)</p> Signup and view all the answers

How are fats typically characterized in terms of their physical state at room temperature?

<p>Fats are solid and predominantly come from animals. (A)</p> Signup and view all the answers

What is a consequence of increasing unsaturation in fatty acids?

<p>Faster deterioration and rancidity. (B)</p> Signup and view all the answers

Which fatty acid is classified as polyunsaturated and has a melting point of -11 °C?

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

What type of reaction is described by the hydrolysis of fatty acids?

<p>The reaction cleaves fatty acids into smaller components using water. (A)</p> Signup and view all the answers

What is the primary function of High Density Lipoproteins (HDLs)?

<p>Transport excess cholesterol to the liver for disposal (A)</p> Signup and view all the answers

Which statement differentiates Low Density Lipoproteins (LDLs) from High Density Lipoproteins (HDLs)?

<p>LDL tends to deposit cholesterol on arterial walls (C)</p> Signup and view all the answers

Which food item has the highest cholesterol content?

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

What type of fatty acids are more prevalent in LDLs compared to HDLs?

<p>Trans fatty acids (B)</p> Signup and view all the answers

What role does 7-dehydrocholesterol play in the body?

<p>It acts as a cholesterol precursor (B)</p> Signup and view all the answers

How is lecithin classified in terms of its chemical composition?

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

What characteristic do all phospholipids share with regard to their structure?

<p>They have a hydrophobic interior and hydrophilic exterior. (A)</p> Signup and view all the answers

Which of the following statements is true about the role of lecithin in food products?

<p>It functions as an emulsifying agent. (C)</p> Signup and view all the answers

Which nutrient is needed for the biosynthesis of phospholipids?

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

What property allows phospholipids to form a bilayer in cell membranes?

<p>They have both polar and nonpolar regions. (D)</p> Signup and view all the answers

Flashcards

Lipids

Organic substances, including fats, oils, steroids, and waxes, that are insoluble in water but dissolve in organic solvents. They are major components of living systems and play crucial roles in energy storage, cell structure, and signaling.

Fatty Acids

The simplest lipids, they usually don't exist alone in nature, but are components of more complex lipids. They are carboxylic acids with a long hydrocarbon chain.

Saturated Fatty Acids

Fatty acids with only single bonds between carbon atoms in their hydrocarbon chain. They are usually solid at room temperature.

Monounsaturated Fatty Acids

Fatty acids with one double bond in their hydrocarbon chain. They are usually liquid at room temperature.

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Polyunsaturated Fatty Acids

Fatty acids with two or more double bonds in their hydrocarbon chain. They are usually liquid at room temperature.

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Unsaturated fatty acid

A type of fatty acid that has at least one double bond in its carbon chain.

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Close Packing

The tendency of molecules to pack together tightly, leading to higher melting points.

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Intermolecular forces

The forces of attraction between molecules, which can influence melting points.

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Triacylglycerol

A compound formed from glycerol and three fatty acid molecules.

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Hydrolysis

A process where water is used to break down a molecule into smaller components.

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Oxidation

The breakdown of a molecule due to oxidation, often leading to spoilage in fats and oils.

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Rancidity

The deterioration of fats and oils due to oxidation, characterized by unpleasant smells and flavors.

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Saponification

The reaction where a triglyceride is broken down into glycerol and three soap molecules.

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Hydrogenation

The process of adding hydrogen atoms to the double bonds in an unsaturated fatty acid.

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Triglyceride

A type of ester formed from the reaction of a fatty acid with glycerol.

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Essential Fatty Acid

A fatty acid that is essential for human health but cannot be synthesized by the human body.

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Omega-3 Fatty Acid

A fatty acid with its first double bond three carbons away from the omega end.

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Cis Fatty Acid

A type of fatty acid where the hydrogen atoms on the double bond are on the same side of the molecule.

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Trans fat

A type of unsaturated fat with a specific structure, where the hydrogen atoms are positioned on opposite sides of the double bond.

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Cholesterol

A complex lipid molecule crucial for cell membrane structure, hormone synthesis, and other vital functions. Found in animal products.

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Lipoproteins

Cholesterol is transported in the bloodstream by these complexes, which are composed of protein, cholesterol, and triglycerides. They play a crucial role in fat and cholesterol transport and metabolism.

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LDL (Low-density lipoprotein)

A type of lipoprotein that carries mainly cholesterol and is known to contribute to heart disease when levels are high.

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What are waxes?

A type of lipid that is a long-chain ester of a fatty acid and a long-chain alcohol. Waxes are waterproof, making them useful for coating feathers, leaves, and fruit, and can be used as a sealant in humans.

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How does whale oil work?

A type of fat found in whales that acts as insulation and allows them to dive deeper. It is liquid at surface temperatures but solidifies at depth, increasing density and helping the whale stay submerged.

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What makes soaps and detergents bipolar?

A substance that has both polar and nonpolar parts. The polar 'head' attracts water while the nonpolar 'tail' repels it. This property allows soaps and detergents to clean grease by dissolving it in water.

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How does soap make grease 'water-soluble'?

The process where soap molecules surround grease droplets, forming a sphere called a micelle. This allows the grease to be suspended in water and removed.

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What is hard water?

Water containing high concentrations of calcium, magnesium, and iron ions, which react with soaps to form insoluble salts. Detergents are preferred for hard water because their sulfonate groups are more soluble.

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What are HDL's?

Transports excess cholesterol from the bloodstream to the liver for disposal. It helps to lower bad cholesterol levels in our blood.

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What can happen with LDL's and VLDL's?

Can deposit cholesterol on the walls of arteries, potentially leading to plaque buildup and cardiovascular disease.

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What type of fats are found in HDL?

Unsaturated fats generally have a lower melting point, meaning they are liquid at room temperature. They are often considered healthier than saturated fats.

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What type of fats are found in LDL?

Saturated fats are generally solid at room temperature and are often found in animal products. They can contribute to higher cholesterol levels.

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What are phospholipids?

A type of lipid that forms the structural basis of cell membranes. They have a polar head and a non-polar tail, allowing them to create a barrier between the inner and outer cell environments.

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What is lecithin?

A type of phospholipid commonly found in egg yolks. It acts as an emulsifier, helping to blend oil and water together in foods.

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What is 7-dehydrocholesterol?

A precursor to vitamin D. It is converted into vitamin D by the action of sunlight on our skin.

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What is Vitamin D?

A vital nutrient produced in our bodies with the help of sunlight. It plays a role in calcium absorption and bone health.

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What are phosphatidic acids?

A complex molecule composed of a glycerol backbone, two fatty acids, and a phosphate group. They are essential for cell structure and function.

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What is a phospholipid bilayer?

Also known as the cell membrane, this structure is composed of a double layer of phospholipids. It acts as a barrier that controls what enters and exits the cell.

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Study Notes

Lipids

  • Lipids are organic substances found in living systems.

  • They are insoluble in water but soluble in organic solvents.

  • Lipids have mostly carbon and hydrogen atoms. Some also have a few polar atoms/functional groups.

  • Lipids include fats, oils, steroids, and waxes.

  • Fats and oils make up 95% of nutritional lipids; the remaining 5% are steroids and other functional lipids.

  • Fats are solid triglycerides.

  • Oils are liquid triglycerides.

  • Lipids are classified as simple, complex, and derived lipids.

  • Simple lipids include fats and oils (triglycerides), waxes, steroids, and fat-soluble vitamins.

  • Complex lipids include phospholipids and glycolipids.

  • Derived lipids include steroids, fat-soluble vitamins, and others.

  • Simple lipids are esters of fatty acids (FAs) with various alcohols.

  • Neutral fats/oils: The alcohol is glycerol.

  • Waxes: The alcohol is any alcohol other than glycerol.

  • Complex lipids are products of hydrolysis that have FAs and an alcohol with additional prosthetic groups.

  • Examples of complex lipids: Phospholipids, Glycolipids, Lipoproteins

  • Lipids have several important functions:

  • Storage form of energy

  • Structural component of cell membranes

  • Precursor of many steroid hormones

  • Protection of internal organs

  • Vitamin D precursor

Fatty Acids

  • Fatty acids are long-chain carboxylic acids.
  • They typically have 12-18 carbon atoms.
  • They are insoluble in water.
  • They are either saturated or unsaturated.
  • Saturated fatty acids have only single bonds between carbon atoms.
  • Monounsaturated fatty acids have one double bond between carbon atoms.
  • Polyunsaturated fatty acids have two or more double bonds between carbon atoms.

Saturated Fatty Acids

  • Molecules fit closely together in a regular pattern
  • Strong attractions (dispersion forces) between fatty acid chains
  • High melting points, making them solids at room temperature.
  • Some examples are capric acid (10 C atoms), lauric acid (12 C atoms), myristic acid (14 C atoms), palmitic acid (16 C atoms), stearic acid (18 C atoms), and arachidic acid (20 C atoms).

Unsaturated Fatty Acids

  • Fatty acid chains are non-linear; the molecules do not pack closely together
  • Weak attractions (dispersion forces) between chains
  • Lower melting points, hence are liquids at room temperature.
  • Oleic acid and linoleic acid are examples.

Triacylglycerols

  • Also known as triglycerides
  • Major form of fatty acid storage in plants and animals
  • Fats are solid at room temperature
  • Oils are usually liquid at room temperature

Reactions (Metabolic)

  • Fatty acids, when oxidized, decompose into smaller carbon molecules (C2 pieces) releasing CO2, water, and energy.

Reactions (Synthetic)

  • Unsaturated fatty acids can be converted to saturated fatty acids through hydrogenation.
  • Oxidation to decomposition is an easy process in unsaturated fatty acids and more difficult in saturated fatty acids

Saponification/Hydrolysis

  • Treating triglycerides with a strong base (e.g., sodium hydroxide) breaks the ester bonds to produce glycerol and soap.
  • Hydrolysis is the breakdown of a compound into other substances through the action of water.

Omega-3 Fatty Acids

  • Mostly found in fish oils
  • Contain mostly 20 and 22 carbons polyunsaturated fatty acids
  • The first double bond is 3 carbons away from the omega end.
  • Examples include EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), and Alpha linolenic acid

Cis vs Trans Fatty Acids

  • Almost all natural unsaturated fatty acids have cis geometry in their double bonds.
  • Small amounts of trans fatty acids are found in ruminating animals.

Cholesterol

  • A steroidal alcohol.
  • Found in animal fats and dairy products.
  • Important component of cell membranes
  • Can lead to atherosclerosis if levels are too high

Properties of Cholesterol

  • Very insoluble in water
  • Solid at room temperature.
  • Compact, stiff, rigid structure

Cell Membrane Structure (Lipid Bilayer)

  • A key structural component of cells
  • Cholesterol participates in this structure.

Cholesterol Transport

  • Cholesterol is not water-soluble; therefore, it is transported via lipoproteins.
  • High-density lipoproteins (HDLs) transport cholesterol to the liver for removal ("good cholesterol").
  • Low-density lipoproteins (LDLs) and very-low-density lipoproteins (VLDLs) can deposit cholesterol in arterial walls ("bad cholesterol").

Structural Features (HDL vs LDL)

  • HDLs contain unsaturated cis fatty acids;
  • LDLs contain more saturated and trans fatty acids.
  • Both contain apolipoproteins and phospholipids.

Phospholipids

  • Phospholipids are composed of polar heads and nonpolar tails for cell membranes.
  • Phospholipids act like surfactants, which help solubilize fats in water.
  • Lecithins are a type of phospholipid.
  • Phospholipids are biosynthesized by humans from phosphatidic acids and fatty acids. ATP is also needed as a phosphorylating agent.

Waxes

  • Fatty acid esters with long-chain alcohols.
  • Used for waterproofing and other protective purposes by various organisms.
  • Examples include beeswax, palm wax, and others.

Soaps & Detergents

  • Soaps and detergents have nonpolar tails and polar heads.
  • The nonpolar portion interacts with grease, facilitating removal.
  • The polar portion interacts with water.
  • Synthetic surfactants are categorized into anionic, nonionic, and cationic detergents.

Soaps in Hard Water

  • Hard water contains high amounts of metal ions (Fe, Ca, Mg).
  • These ions form insoluble salts with soap, resulting in a curd.
  • Detergents function well in hard water because sulfonates are soluble in hard water.

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Test your knowledge on the various types of lipids and fatty acids with this quiz. Explore questions about nutritional lipids, the characteristics of saturated vs unsaturated fatty acids, and the role of cholesterol in the body. Ideal for nutrition or biology students.

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