LIPIDS
1. Simple - esters of fatty acids with various alcohols
a. fats - esters of fatty acids with glycerol
Oils are fats in the liquid state
b. waxes - esters of fatty acids with higher molecular weight monohydric alcohols
2. Complex - esters of fatty acids containing groups in addition to an alcohol & a fatty acid
a. phospholipids = fatty acid + alcohol + phosphoric acid residue
- have nitrogen-containing bases & other substituents
Ex: glycerophospholipids - alcohol is glycerol
Sphingophospholipids - alcohol is sphingosine
b. glycolipids / glycosphingolipids = fatty acid + sphingosine + carbohydrate
c. other complex lipids - sulfolipids, aminolipids, lipoproteins
3. Precursor & derived lipids
- fatty acids, glycerol, steroids, other alcohols, fatty aldehydes & ketone bodies, hydrocarbons, lipid-soluble vitamins, & hormones
Neutral lipids - uncharged
- acylglycerols / glycerides, cholesterol & cholesteryl esters
FATTY ACIDS ARE ALIPHATIC CARBOXYLIC ACIDS
Free fatty acids - unesterified
Neutral fats & oils - esterified
- straight-chain derivatives containing an even # of C atoms
Saturated - no double bond
Unsaturated - 1 or more double bonds
FATTY ACIDS ARE NAMED AFTER CORRESPONDING HYDROCARBONS
- named after the hydrocarbon with the same # & arrangement of C atoms
- Saturated - anoic
Unsaturated - enoic
- C atoms are numbered from the carboxyl C
- terminal methyl C is known as the or n-carbon
SATURATED FATTY ACIDS CONTAIN NO DOUBLE BONDS
- based on acetic acid (CH3-COOH) as the 1st member of the series in which CH2 is added between the terminal CH3 & COOH groups
UNSATURATED FATTY ACIDS CONTAIN 1 OR MORE DOUBLE BONDS
1. Monounsaturated acids- 1 double bond
- monoethenoid, monoenoic
2. Polyunsaturated acids - 2 or more double bonds
- polyethenoid, polyenoic
3. Eicosanoids - derived from 20 C polyenoic fatty acids
a. prostanoids
- prostaglandins
*synthesized in vivo by cyclization of the center of the C chain of 20 C polyunsaturated fatty acids (arachidonic acid) to
form a cyclopentane ring
*E type - has a keto group in position 9
F type - hydroxyl group in position 9
- prostacyclins
- thromboxanes
*have the cyclopentane ring interrupted with an O atom (oxane ring)
b. Leukotrienes
-cause bronchoconstriction as well as being potent proinflammatory agents & play a part in asthma
c. lipoxins
(b&c) - 3rd group of eicosanoid derivatives formed via the lipoxygenase pathway
- characterized by 3 or 4 conjugated double bonds
MOST NATURALLY OCCURRING UNSATURATED FATTY ACIDS HAVE CIS DOUBLE BONDS
Saturated - C chains form a zigzag pattern when extended, as at low temperatures
- at high temperatures, some bonds rotate causing chain shortening which explains why biomembranes become thinner
Unsaturated - geometric isomerism occurs depending on the orientation of atoms or groups around the axes of double bonds which do not
allow rotation
1. Cis - acyl chains are on the same side of the bond
- naturally occurring unsaturated long-chain fatty acids
- molecules being bent 120 degrees at the double bond
- oleic acid - L shape
- increase in # of cis double bonds leads to a variety of possible spatial configurations of the molecule
- arachidonic acid - 4 cis double bonds & has kinks or U shape
2. Trans - acyl chains are on opposite sides
- elaidic acid - straight
1. Simple - esters of fatty acids with various alcohols
a. fats - esters of fatty acids with glycerol
Oils are fats in the liquid state
b. waxes - esters of fatty acids with higher molecular weight monohydric alcohols
2. Complex - esters of fatty acids containing groups in addition to an alcohol & a fatty acid
a. phospholipids = fatty acid + alcohol + phosphoric acid residue
- have nitrogen-containing bases & other substituents
Ex: glycerophospholipids - alcohol is glycerol
Sphingophospholipids - alcohol is sphingosine
b. glycolipids / glycosphingolipids = fatty acid + sphingosine + carbohydrate
c. other complex lipids - sulfolipids, aminolipids, lipoproteins
3. Precursor & derived lipids
- fatty acids, glycerol, steroids, other alcohols, fatty aldehydes & ketone bodies, hydrocarbons, lipid-soluble vitamins, & hormones
Neutral lipids - uncharged
- acylglycerols / glycerides, cholesterol & cholesteryl esters
FATTY ACIDS ARE ALIPHATIC CARBOXYLIC ACIDS
Free fatty acids - unesterified
Neutral fats & oils - esterified
- straight-chain derivatives containing an even # of C atoms
Saturated - no double bond
Unsaturated - 1 or more double bonds
FATTY ACIDS ARE NAMED AFTER CORRESPONDING HYDROCARBONS
- named after the hydrocarbon with the same # & arrangement of C atoms
- Saturated - anoic
Unsaturated - enoic
- C atoms are numbered from the carboxyl C
- terminal methyl C is known as the or n-carbon
SATURATED FATTY ACIDS CONTAIN NO DOUBLE BONDS
- based on acetic acid (CH3-COOH) as the 1st member of the series in which CH2 is added between the terminal CH3 & COOH groups
UNSATURATED FATTY ACIDS CONTAIN 1 OR MORE DOUBLE BONDS
1. Monounsaturated acids- 1 double bond
- monoethenoid, monoenoic
2. Polyunsaturated acids - 2 or more double bonds
- polyethenoid, polyenoic
3. Eicosanoids - derived from 20 C polyenoic fatty acids
a. prostanoids
- prostaglandins
*synthesized in vivo by cyclization of the center of the C chain of 20 C polyunsaturated fatty acids (arachidonic acid) to
form a cyclopentane ring
*E type - has a keto group in position 9
F type - hydroxyl group in position 9
- prostacyclins
- thromboxanes
*have the cyclopentane ring interrupted with an O atom (oxane ring)
b. Leukotrienes
-cause bronchoconstriction as well as being potent proinflammatory agents & play a part in asthma
c. lipoxins
(b&c) - 3rd group of eicosanoid derivatives formed via the lipoxygenase pathway
- characterized by 3 or 4 conjugated double bonds
MOST NATURALLY OCCURRING UNSATURATED FATTY ACIDS HAVE CIS DOUBLE BONDS
Saturated - C chains form a zigzag pattern when extended, as at low temperatures
- at high temperatures, some bonds rotate causing chain shortening which explains why biomembranes become thinner
Unsaturated - geometric isomerism occurs depending on the orientation of atoms or groups around the axes of double bonds which do not
allow rotation
1. Cis - acyl chains are on the same side of the bond
- naturally occurring unsaturated long-chain fatty acids
- molecules being bent 120 degrees at the double bond
- oleic acid - L shape
- increase in # of cis double bonds leads to a variety of possible spatial configurations of the molecule
- arachidonic acid - 4 cis double bonds & has kinks or U shape
2. Trans - acyl chains are on opposite sides
- elaidic acid - straight
