Lipids: Fats, Waxes, and Complex Lipids
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Questions and Answers

What is the chemical formula for Palmitoleic acid?

  • C15H29COOH (correct)
  • C19H31COOH
  • C17H33COOH
  • C17H31COOH
  • What is the number of double bonds in Linoleic acid?

  • 2 (correct)
  • 3
  • 1
  • 4
  • What is the symbol for Oleic acid?

  • 16:1-9
  • 18:2-9,12
  • 18:3-9,12,15
  • 18:1-9 (correct)
  • What is the name of the acid with a symbol 20:4-5,8,11,14?

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

    How are the omega fatty acids classified?

    <p>By the position of the first double bond from the CH3 end</p> Signup and view all the answers

    What is the chemical name of the acid with the symbol 18:3-6,9,12?

    <p>Gama-linolenic acid</p> Signup and view all the answers

    What determines the type of fatty acid in the omega family?

    <p>The position of the first double bond from the CH3 end</p> Signup and view all the answers

    What symbol represents the acid with 1 double bond and 16 carbons?

    <p>16:1-9</p> Signup and view all the answers

    How many double bonds does Alpha-linolenic acid have?

    <p>3</p> Signup and view all the answers

    What is the chemical name of the acid with the symbol 18:1-9?

    <p>cis 9-Octadecenoic acid</p> Signup and view all the answers

    Study Notes

    Lipids: Fats and Waxes

    • Lipids include complex lipids (diacylglycerols, fatty acids, alcohols, sterols, vitamins D, E, K, carotenoids, terpenes, eicosanoid compounds) and neutral lipids (acylglycerols, cholesterol, cholesteryl esters)

    Fatty Acids

    • Fatty acids are aliphatic mono-carboxylic acids, mainly occurring in triglycerides
    • They have a hydrocarbon chain (mostly even-numbered, 4-20 carbons long) with a carboxyl group at the end
    • Naturally occurring saturated fatty acids are volatile liquids at room temperature, below 8 carbons
    • Waxes have 34 carbon atoms, while bacterial waxes can have up to 90 carbon atoms

    Saturated Fatty Acids

    • Saturated fatty acids have no double bonds in their hydrocarbon chain
    • Palmitic and stearic acids are the most abundant fatty acids in humans
    • Lignoceric acid is a component of cerebrosides
    • Systemic names for saturated fatty acids include palmitic acid (n-hexadecanoic acid), stearic acid (n-octadecanoic acid), and arachidic acid (n-eicosanoic acid)

    Important Saturated Fatty Acids

    • Acetic acid (2:0), butyric acid (4:0), caproic acid (6:0), palmitic acid (16:0), stearic acid (18:0), arachidic acid (20:0), and lignoceric acid (24:0)

    Unsaturated Fatty Acids

    • Unsaturated fatty acids possess one or more double bonds in their hydrocarbon chain
    • They are more reactive than saturated fatty acids
    • Monounsaturated fatty acids have one double bond, while polyunsaturated fatty acids have more than one double bond
    • Oleic and palmitoleic acids are abundant in humans
    • Dienoic, trienoic, and tetraenoic fatty acids have 2, 3, and 4 double bonds, respectively

    Important Unsaturated Fatty Acids

    • Palmitoleic acid (16:1 ω-7), oleic acid (18:1 ω-9), linoleic acid (18:2 ω-6,9), alpha-linolenic acid (18:3 ω-3,6,9), gamma-linolenic acid (18:3 ω-6,9,12), and arachidonic acid (20:4 ω-5,8,11,14)

    Melting Point of Fatty Acids

    • Melting points of saturated fatty acids increase with increasing hydrocarbon chain length
    • Melting points of unsaturated fatty acids decrease with increasing number of double bonds
    • Examples: butyric acid (8°C), palmitic acid (62°C), stearic acid (70°C), oleic acid (14°C), linoleic acid (-5°C), and arachidonic acid (-50°C)

    Solubility of Fatty Acids

    • Terminal COOH ionizes to become anionic (-COO¯), increasing water solubility
    • Hydrophilicity increases solubility, while hydrophobicity decreases solubility
    • Solubility decreases with increasing hydrocarbon chain length
    • Presence of double bonds increases solubility

    Isomerism in Fatty Acids

    • In saturated fatty acids, they can be straight chains or branched
    • In unsaturated fatty acids, presence of double bonds causes geometric isomerism (cis or trans)
    • In mammals, all unsaturated fatty acids are cis
    • Cis configuration causes a rigid bend in the hydrocarbon chain

    Nutritionally Essential Fatty Acids

    • Certain fatty acids must be taken in by humans, as they cannot be synthesized by the body
    • Examples: linoleic acid and alpha-linolenic acid (polyunsaturated fatty acids)

    Chemical Properties of Fatty Acids

    • Formation of salts (soaps) with alkali or alkaline earth metals
    • Sodium and potassium soaps are soluble, while calcium and magnesium soaps are insoluble

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    Description

    This quiz covers the basics of lipids, including fatty acids, waxes, and complex lipids. It includes examples of hydrolytic products, neutral lipids, and fatty acid characteristics.

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