清华大学：《生物化学》课程PPT教学课件（英文版）Biological molecules（IV）

Beta-sheet Hydrogen R c

Beta-sheet

Alpha-helix Amino terminus 5.4A (3. 6 residues) CArbon O Hydroge Oxygen NItrogen OR group Carboxyl terminus

Alpha-helix

Example of polypeptide IgG

Example of polypeptide : IgG

Biological molecules (Iv): Lipids Lipids are a class of nonpolar molecules that include the fats cholesterol, fatty acids, lipid-soluble vitamins, waxes, soaps, glycerophospholipids, sphingolipids, and others. Lipids are found in the membranes of cells, the endoplasmic reticulum and in specialized fat storage cells called adipocytes. Example of lipids Fat (Triacylglycerols ): Fats are composed of glycerol esterified to three fatty acids. Fats are derived from three primary sources:(1)the diet;(2)de novo biosynthesis, particularly in liver; and (3) storage depots in adipocytes

Biological molecules (IV): Lipids Lipids are a class of nonpolar molecules that include the fats, cholesterol, fatty acids, lipid-soluble vitamins, waxes, soaps, glycerophospholipids, sphingolipids, and others. Lipids are found in the membranes of cells, the endoplasmic reticulum, and in specialized fat storage cells called adipocytes. Example of Lipids: Fat (Triacylglycerols) : Fats are composed of glycerol esterified to three fatty acids. Fats are derived from three primary sources: (1) the diet; (2) de novo biosynthesis, particularly in liver; and (3) storage depots in adipocytes

Bilayer lipid membrane Hydrophobic Inner aqueous tails compartment Hydrophilic surfaces Liposome

Bilayer lipid membrane

Stomach Gallbladder emulsifiers Pancreas Smail intestine diacylglycerols contains hydrolytic Processes by which transported nzymes rom fats are utilized in bloodstream via Triacylglycerols animals are lipoproteins transported summarized here Storage as through the triacylglycerols bloodstream via Breakdown of fats ssue chylomicrons Falty acids by lipases yields associated with albumin fatty acids and Muscle glycerol

Processes by which fats are utilized in animals are summarized here. Breakdown of fats by lipases yields fatty acids and glycerol

Fatty acid species Acid Stearic Oleic Linoleic a-Linolenic of carbons 18 18 18 Degree of unsaturation 18:0 18:1 18:2 18:3 0、OH 0、OH Q、OH 0、OH Structure (all double bonds are cis)

Fatty acid species

H-C-0-C-CH2 H-C-0-C-CH2 0 0 H-C-0-C-CH2 H-C-O-C-CH2 0 H-C-0-C-CH2MM H-c-0-9-cH2 H H Fat oil Triglycerides

Cholesterol H3C C H CH3 CH3 HO Cholesterol Cholesterol is a member of a large group of substances called steroids. which include vitamin d and a number of steroid hormones, among them the sex hormones of higher animals. In fact, cholesterol is the precursor for the synthesis of many of these substances and is also a precursor of the bile acids

Cholesterol Cholesterol is a member of a large group of substances called steroids, which include vitamin D and a number of steroid hormones, among them the sex hormones of higher animals. In fact, cholesterol is the precursor for the synthesis of many of these substances and is also a precursor of the bile acids

Lipid-Soluble Vitamins Vitamins A, D, E, and K are lipid-soluble. Although one of these, Vitamin D, is ultimately derived from cholesterol, the other three are not CHa H3C CH3 CH CH3 Chemical structure of vitamin d CH vitamin D HO

Lipid-Soluble Vitamins Vitamins A, D, E, and K are lipid-soluble. Although one of these, Vitamin D, is ultimately derived from cholesterol, the other three are not. Chemical structure of Vitamin D