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3 H 2O O
H
O
H
H
C
O H + HO
C O
(CH 2 ) n
CH3
H
C
O
C O
(CH 2 ) n
CH3
H
C
O H + HO
C O
(CH 2 ) n
CH3
H
C
O
C O
(CH 2 ) n
CH3
H
C
O H + HO
C
(CH 2 ) n
CH3
H
C
O
C
(CH 2 ) n
CH3
H Glycerol
H 3 Fatty Acids
Ester Linkage
B. Fatty acid chains can vary in length & degree of saturation (see below) C. 3 fatty acids of triglyceride need not be identical but may be; if they contain more than one fatty acid species called mixed fats 1. Most natural fats (olive oil, butter fat) - mixtures of molecules with different fatty acid species III. Fatty acids - long, unbranched hydrocarbon chains with single carboxyl group at one end A. Both hydrophobic (long C chain) & hydrophilic (carboxyl; “-“ charge at physiological pH) in character (amphipathic); they have unusual & biologically important properties B. Fatty acids can differ in size (usually even & 14 to 20 carbons) & degree of saturation (presence or absence of double bonds) 1. Saturated chains have no double bonds; every C attached to maximum number of H's; chains straight, pack tightly together (solid above room temperature [stearic acid, animal fats]) a. Tristearate's fatty acids lack double bonds, is a common component of animal fats & remains in a solid state well above room temperature 2. Unsaturated chains - 1 or a few double bonds (each causes bend/kink & if in cis configuration prevents tight packing); if prevalent, liquid at room temperature (ex.: plant fats called oils) a. In oils, double bonds lower the temperature at which a fatty acid containing lipid melts b. Multiple double bonds leads to oils being called polyunsaturated c. Example: linseed oil – highly volatile lipid extracted from flax seeds, remains liquid at much lower temperatures than tristearate C. Soap - in past, soap was made by heating animal fat in strong alkali (NaOH, KOH) to break fatty acid - glycerol bonds; most are now made synthetically 1. Hydrophobic end of fatty acids embed in grease; hydrophilic end interacts with water 2. Greasy materials form complexes that can be dispersed by water (micelles) D. Margarine formed from unsaturated vegetable oils by chemically reducing double bonds with H atoms (hydrogenation) IV. Sterols and steroids – complex & characteristic 4 ringed hydrocarbon structures (4 joined rings differ in numbers & positions of double bonds & functional groups) A. Most common & one of most important - cholesterol; a component of animal cell membrane, but not in internal membranes or in plants 1. Precursor for synthesis of many steroid hormones (testosterone, progesterone, estrogen) 2. While largely absent from plant cells (vegetable oils considered to be cholesterol-free), plants may contain lots of related compounds B. Adrenocortical hormones C. Sex hormones - estrogen, progesterone, testosterone, etc.
36 Full file at https://testbankuniv.eu/Cell-and-Molecular-Biology-Concepts-and-Experiments-7th-Edition-Karp-Solutions-Manual