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Lipids
are non polar compounds that are not in water, but soluble in organic solvents. Includes waxes, fats and oils, glycerophospholipids and steroids.
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Lipids that conatain no fatty acids:
Steroids.
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A Fatty acid:
contains a long unbranched carbon chain attached to a carboxylic acid group at one end.
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A Saturated Fatty acid:
contains only one carbon-carbon bonds. (properties similar to an alkane.)
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In a Monounsaturated fatty acid:
the long carbon chain has one double bond. (properties similar to an alkene.)
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A Polyunsaturated fatty acid:
has at least two carbon-carbon double bonds.
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Lauric Acid:
Saturated Fatty Acid, 12 Carbon atoms. CH3--(CH2)10--COOH
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Myristic Acid:
Saturated Fatty Acid, 14 Carbon Atoms: CH3--(CH2)12--COOH
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Palmitic Acid:
Saturated Fatty Acid, 16 Carbons: CH3--(CH2)14--COOH
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Stearic Acid:
Saturated Fatty Acid, 18 Carbons: CH3--(CH2)16--COOH
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Palmitoleic acid:
Monounsaturated Fatty acid: 16 Carbons CH3--(CH2)5--CH==CH--(CH2)7--COOH
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Oleic Acid:
Monounsaturated Fatty Acids; 18 Carbons CH 3--(CH 2) 7--CH==CH--(CH 2) 7--COOH
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Linoleic Acid:
- Polyunsaturated Fatty Acid; 18 Carbons
- CH3-(CH2)4-CH=CH-CH2-CH=CH-(CH2)7-COOH

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Linolenic Acid:
Polyunsaturated Fatty Acids; 18 Carbons; CH 3--(CH 2--CH==CH) 3--(CH 2) 7--COOH
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Arachidonic Acid:
Polyunsaturated Fatty Acids; 20 Carbons; CH3--(CH2)3--(CH2--CH==CH)4--(CH2)3--COOH
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Prostaglandins:
- hormone-like substances formed from Arachidonic acid.
- raise or lower blood pressure.
- stimulate contraction & relaxation of smooth muscle.
- PGE & PGF produce inflammation and pain.
- NSAIDs block the production of prostaglandins; decrease pain.
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Similarities in the structures of a saturated fatty acid and an unsaturated fatty acid.
All fatty acids contain a long chain of carbon atoms with a carboxylic acid group.
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Differences in the structures of a saturated fatty acid and an unsaturated fatty acid.
Saturated fatty acids contain only carbon-carbon single bonds; unsaturated fatty acids contain one or more double bonds.
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Saturated fatty acids:
- Lauric Acid
- Myristic Acid
- Palmitic Acid
- Stearic Acid
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Monounsaturated acids:
- Palmitoleic Acid
- Oleic Acid
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Polyunsaturated Fatty Acids:
- Linoleic Acid
- Linolenic Acid
- Arachidonic Acid
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How does the structure of a fatty acid with a cis double bond differ from the structure of a fatty acid with a trans double bond?
- In a cis fatty acid the H atoms are on the same side of the double bond (produces a bend in the carbon chain).
- In a trans fatty acid the H atoms are on opposite sides of the double bond (no bond in carbon chain).
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What is the difference in the location of the first double bond in an Omega-3 and an Omega-6 fatty acid?
- Omega-3: double bond on carbon 3 (counting from methyl group).
- Omega-6: double bond on carbon 6 (counting from methyl group).
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Sources of Omega-3 fatty acids:
fish oils (linolenic acid).
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Sources of Omega-6 fatty acids:
- vegetable oils.
- meat (land animals)
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Compare Arachidonic acid and Prostagland E (PGE):
- arachiodonic acid has four double bonds and no side group.
- PGE1 has cyclopentane, and hydroxyl and ketone functional groups.
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Compare structures of and functional groups of PGE and PGF
- PGE has a ketone group on carbon 9.
- PGF has a Hydroxyl group on carbon 9.
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A Wax is:
an ester of a long-chain saturated fatty acid and a long-chain alcohol; containing 14-30 carbon atoms.
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Wax structure:
Fatty acid(--C==O), ester bond (--O--), Long chain alcohol
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Triacylglycerols:
Triglycerides, are triesters of glycerol (trihydroxy alcohol) and fatty acids.
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The triglycerol that is formed by the esterification of glycerol with CH3--(CH2)12--COOH:
- The saturated fatty acid is: Myristic acid.
- It forms glyceryl trimystate or trimyristin (common).
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The triglycerol that is formed by the esterification of glycerol with CH3--(CH2)5--CH==CH--(CH2)7--COOH:
- The monounsaturated fatty acid with 16 carbons is Palmitoleic acid.
- It forms glyceryl tripalmitoleate or tripalmitolein (common).
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A Fat is:
- A triacylglycerol that is solid at room temperature.
- Obtained from an animal source (meat, whole milk, butter & cheese).
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An Oil is:
- A triacylglycerol that is usually a liquid at room temperature.
- Obtained from a plant source.
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In Hydrogenation of an unsaturated fat:
hydrogen is added to carbon-carbon double bonds to form carbon-carbon single bonds.
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Esterification Reaction:
Glycerol + 3 Fatty Acid molecules --> triacylglycerol + 3H2O
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Hydrogenation of Triacylglycerols:
Tracylglycerol (unsaturated) + H2 -(Ni)->Triacylglycerol (saturated).
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Oxidation of Unsaturated Fatty Acids:
Fatty Acids (unsaturated) --> (short-chain aldehydes) --> (short-chain carboxylic acids)
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Hydrolysis of Triacylglycerols:
Triacylglycerol + 3H2O -HCl-> glycerol + 3 fatty acid molecules
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Saponification of Triacylglycerols:
Triacylglycerol + 3NaOH --> glycerol + 3 sodium salts of fatty acids
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Biodiesel:
A nonpetroleum fule that can be used in place of diesel fuel; produced from renewable biological resources.
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Cephalin:
A glycerophospholipid found in brain and nerve tissues that incorporates the amino alcohol serine or ethanolamine.
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Ceramide:
A lipid in which sphingosine is attached to a fatty acid by an amide link.
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Cholesterol:
The most prevalent of the steroid compounds; needed for cellular membranes and the synthesis of vitamin D, hormones, and bile salts.
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Fatty Acid:
A long-chain carboxylic acid found in many lipids.
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Lecithins:
Glycerophospholipids containing choline as the amino alcohol.
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