Introduction to Lipids
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Questions and Answers

What role does cholesterol play in the plasma membrane?

  • Makes the membrane more fluid
  • Increases membrane stability (correct)
  • Prevents the entry of nonpolar molecules
  • Activates protein channels

    • Facilitated diffusion requires energy to occur.

    False

    What is the most abundant steroid in animals?

    Cholesterol

    Bile salts aid in the digestion and absorption of dietary __________.

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

    Match the following types of lipoproteins with their function:

    <p>Low-density lipoproteins (LDLs) = Transport lipids from liver to cells High-density lipoproteins (HDLs) = Transport lipids from cells to liver</p> Signup and view all the answers

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

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

    Triacylglycerols (TAGs) are formed from two fatty acids and glycerol.

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

    What is the primary structural difference between fats and oils?

    <p>Fats are solid/semi-solid at room temperature while oils are liquid.</p> Signup and view all the answers

    Sphingolipids contain ______, a long chain N-containing alcohol.

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

    Match the following lipid types with their descriptions:

    <p>Phospholipids = Most common membrane lipids Sphingolipids = Contain sphingosine and fatty acids Triacylglycerols = Formed from three fatty acids Micelles = Spherical structures with hydrophobic cores</p> Signup and view all the answers

    Which of the following is NOT a function of lipids?

    <p>Acting as catalysts for chemical reactions</p> Signup and view all the answers

    Triacylglycerols provide 7 kcal of energy per gram.

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

    What are the four lipid-soluble vitamins?

    <p>A, D, E, K</p> Signup and view all the answers

    Saturated and unsaturated fatty acids are classified as __________ lipids.

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

    Which type of lipid contains an aminoalcohol sphingosine?

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

    Match the types of lipids with their descriptions:

    <p>Phospholipids = Contain phosphoric acid and often a nitrogenous base Waxes = Esters of fatty acids with fatty alcohols Lipoproteins = Lipids attached to plasma or other proteins Lipopolysaccharides = Lipids attached to polysaccharides</p> Signup and view all the answers

    Lipoproteins are simple lipids consisting only of fatty acids.

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

    __________ is found in shark and mammalian liver and in human sebum.

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

    Which type of lipid is typically solid at room temperature?

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

    Fatty acids can be both saturated and unsaturated.

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

    What is the IUPAC name of stearic acid?

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

    _____ are lipids that serve as messengers in the body.

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

    Which of the following fatty acids is classified as monounsaturated?

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

    Match the following fatty acids with their respective shorthand notations:

    <p>Linoleic acid = 18:2(Δ9,12) Oleic acid = 18:1(Δ9) Arachidonic acid = 20:4(Δ5,8,11,14) EPA = 20:5(Δ5,8,11,14,17)</p> Signup and view all the answers

    All fatty acids have an even number of carbon atoms.

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

    Name one essential fatty acid.

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

    Study Notes

    Introduction to Lipids

    • Lipids are biological compounds that are insoluble or sparingly soluble in water.
    • They include lipid-soluble vitamins (A, E, D, K).
    • Lipids serve as major energy reserves in the body, primarily as triacylglycerols (triglycerides).
    • They provide 9 kcal of energy per gram.
    • Lipids insulate body organs.
    • Lipids are structural components of cell membranes.
    • Lipids are intercellular chemical messengers and aid in lipid solubilization.

    Classification of Lipids Based on Structure

    • Simple Lipids: Esters of fatty acids with various alcohols.

      • Natural fats and oils (triacylglycerols): Naturally occurring fats and oils.
      • Waxes:
        • True waxes: Cetyl alcohol esters of fatty acids.
        • Other types of waxes.
      • Cholesterol Esters
      • Vitamin A Esters
      • Vitamin D Esters

    • Compound Lipids: Esters of fatty acids with alcohol plus other groups.

      • Phospholipids: Contain phosphoric acid and a nitrogenous base.
      • Sphingolipids: Contain an amino alcohol (sphingosine) and some include glycolipids and cerebrosides.
      • Sulfolipids: Contain a sulfate group.
      • Lipoproteins: Lipids attached to plasma/other proteins.
      • Lipopolysaccharides: Lipids attached to polysaccharides.

    Derived Lipids

    • Hydrolytic products of simple and compound lipids
      • Saturated and unsaturated fatty acids: Fatty acids that are saturated, or have one or more carbon-carbon double bonds
      • Monoacylglycerols and diacylglycerols: glycerols that have one or two fatty acids attached.
      • Alcohols (β-carotenoid ring): like β-carotene

    Miscellaneous Lipids

    • Aliphatic HC: In liver fat and certain hydrocarbons in beeswax and plant waxes.
    • Squalene: Found in shark and mammalian liver as well as human sebum.
    • Vitamins A, D, E, and K: Fat-soluble vitamins.

    Lipids with Fatty Acids

    • Waxes: Protective coatings.
    • Triacylglycerols: Energy storage.
    • Phospholipids: Components of cell membranes.
    • Sphingolipids: (structural) components of cell membranes.
    • Steroids: (cholesterol) act as messengers.
    • Bile acids: Assist in lipid emulsification.

    Lipids without Fatty Acids

    • Steroids: Have a fused ring system, including cholesterol.
    • Cholesterol: Crucial for animal cells and precursor of other steroids.
    • Bile salts: Help digest and absorb dietary fats.
    • Prostaglandins: Derived from arachidonic acid. Play a role in pain, fever, and other bodily functions.
    • Leukotrienes: Involved in allergic and inflammatory responses.
    • Lipoproteins: Complexes of lipids and proteins required for transporting lipids in the blood.

    Fatty Acids

    • Naturally occurring monocarboxylic acids.
    • Typically long-chain (10-20 carbon atoms).
    • Often saturated or unsaturated, with double bonds.
    • Saturated fatty acids (SFAs): Pack closely and have high melting points (solids).
    • Monounsaturated fatty acids (MUFAs): Contain one double bond.
    • Polyunsaturated fatty acids (PUFAs): Contain more than one double bond and often have low melting points (liquid).

    Physical Properties of Fatty Acids

    • Solubility in water varies with the length of the carbon chain and pH.
    • Saturated fatty acids have higher melting points than unsaturated fatty acids.
    • Degree of unsaturation affects the melting point.

    Transport Across Membranes

    • Membranes restrict ion and polar molecule movement.
    • Mechanisms for transporting across membranes include simple diffusion, facilitated diffusion, and active transport.
    • Membranes: Semi-permeable Barriers
    • Micelles: Spherical structures, with hydrophobic cores and hydrophilic surfaces; key in the digestion of fats.
    • Bilayers: Phospholipid bilayers have polar (hydrophilic) heads facing the aqueous environment, and non-polar (hydrophobic) tails facing each other.

    Fluid Mosaic Model

    • Plasma membranes have a fluid consistency at body temperature.
    • Proteins and other substances can move across the membrane.
    • Cholesterol makes the membrane stable and prevents it from solidifying.

    Triacylglycerols (TAGs)

    • Triacylglycerols are triesters of fatty acids with glycerol.
    • Fats (saturated) are typically solid at room temperature, while oils (unsaturated) are liquid.

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    Lecture 11_Lipids PDF

    Description

    This quiz covers the basics of lipids, including their structure, function, and classification. Explore the different types of lipids such as simple and compound lipids, their biological roles, and their significance in energy storage and cellular structure. Test your knowledge on lipid-soluble vitamins and their functions.

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