Lipids_Biochem_SS1

Lipids_Biochem_SS1 - Triglycerides, Phospholipids,...

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Unformatted text preview: Triglycerides, Phospholipids, Phospholipids, Sterols and Steroids Provides Calories Provides Insulation Forms Membranes S Forms Sterols Forms Steroids Forms Fat Soluble Vitamins Fatty Acids and Derivatives Triacylglycerols Wax Esters Phospholipids Sphingolipids Isoprenoids Lipoproteins Membranes Membrane Structure Membrane Function Triglycerides (fats and oils) Phospholipids (lecithin) Sterols (cholesterol) and Steroids Composed of Composed 1 glycerol +3 fatty acids fatty Carbon, Hydrogen, Hydrogen 1 double bond: monounsaturated fatty acids An unsaturated fatty acid has one or more carbon­ carbon double bonds in the chain. The first double bond is usually at the ninth carbon. The double bonds are not conjugated and are usually cis. H CH2 O H C C CH2 CH2 CH2 C O CH2 CH CH2 CH2 CH2 2 CH2 CH2 CH2 CH3 Palmitoleic acid, salt form Cis double bond results in a bent chain and lower mp. Stearic 18:0 Palmitoleic Linolenic • CH3(CH2)16COOH 16:1∆ 9 18:2∆ 9,12 • CH3(CH2)5CH=CH (CH2)7COOH • CH3(CH2)4CH=CHCH2CH=CH(CH2)7CO Arachidonic 20:4∆5 ,8,11,14 Length of the chain Length of the chain = number of carbons Number of double bonds = areas where it is not saturated or full of hydrogens • • cis­ to trans­ H H H ­C=C­ ­­­­­­­> ­C=C­ H Changes some of the fatty acids from uusaturated to saturated Shifts some double bonds in fatty acids from cis to trans: In unsaturated fatty acids, there are two Triglycerides Triglycerides 95% Phospholipids & 5% Cholesterol Cholesterol Similar to triglycerides • Glycerol and two polyunsaturated fatty acids • Phosphorus­containing molecule in place of the third fatty acid. Example: Lecithin • Used as an emulsifier • Also found naturally in foods (eggs, liver) OO CH3 CH3 CH2 C CH CH2 CH2 C CH2CH2 O P O P O OO isoprene unit isopentenylpyrophosphate OH geraniol farnesene phytol OH β -carotene Large complex lipid compounds containing interconnected rings of carbon atoms Examples: • Cholesterol • Steroid hormones • Vitamin D Steroids are based on the ring system shown below also derived of ISOPRENE units. Next are some examples of steroid sex hormones and of cholesterol, a lipid very important in human physiology. 2 3 11 1 9 10 12 13 17 C 8 7 D 14 16 15 A 4 5 B 6 CH3 Cholesterol CH CH2 CH2 CH2 CH(CH3)2 CH3 H CH3 H H H HO H CH3 CH3 CH3 OH progesterone CH3 CH3 CO O O testosterone Important in the structure of brain and nerve cells Precursor of other important sterols • Cholesterol is a component of every cell • Bile: functions as an emulsifier Human erythrocyte Protein % 49 Lipid % 43 Carb. % 8 Mouse liver Mitochon­ drial (inner) Spinach lamellar 46 76 54 24 2­4 1­2 70 30 6 CH2 CH CH CH CH CH2 12 CH3 O NH OH CH2OH C O A cerebroside O H H R1 OH H HO H H OH Fig. 5.2 Fig. Fig. 15.3 Fig. Fig. 15.4 Fig. Fig. 15.5 Fig. Fig. 15.7 Fig. Fig. 15.8 Fig. ...
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