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Questions and Answers
What is the chemical formula for Palmitoleic acid?
What is the chemical formula for Palmitoleic acid?
What is the number of double bonds in Linoleic acid?
What is the number of double bonds in Linoleic acid?
What is the symbol for Oleic acid?
What is the symbol for Oleic acid?
What is the name of the acid with a symbol 20:4-5,8,11,14?
What is the name of the acid with a symbol 20:4-5,8,11,14?
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How are the omega fatty acids classified?
How are the omega fatty acids classified?
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What is the chemical name of the acid with the symbol 18:3-6,9,12?
What is the chemical name of the acid with the symbol 18:3-6,9,12?
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What determines the type of fatty acid in the omega family?
What determines the type of fatty acid in the omega family?
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What symbol represents the acid with 1 double bond and 16 carbons?
What symbol represents the acid with 1 double bond and 16 carbons?
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How many double bonds does Alpha-linolenic acid have?
How many double bonds does Alpha-linolenic acid have?
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What is the chemical name of the acid with the symbol 18:1-9?
What is the chemical name of the acid with the symbol 18:1-9?
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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.
