PPT-Cholesterol and Steroid Metabolism

UNIT III Lipid Metabolism HDL comprise a heterogeneous family of lipoproteins with a complex metabolism that is not yet completely understood HDL particles are formed in blood by the addition of lipid to . Dr. Nikhat Siddiqi. 1. Overview. Cholesterol, the characteristic steroid alcohol of animal tissues, performs a number of essential functions in the body. . C. holesterol is a structural component of all cell membranes, modulating their fluidity, and, in specialized tissues, cholesterol is a precursor of bile acids, steroid hormones, and vitamin D. . 5/e. Karen C. Timberlake. © 2016 Pearson Education, Inc.. 17.6 Steroids: Cholesterol, Bile Salts, and Steroid Hormones. High- and low-density lipoproteins transport cholesterol between the tissues and the liver.. BIOSYNTHESIS OF CHOLESTEROL. Cholesterol is doubtless the most publicized lipid, notorious because of the strong correlation between high levels of cholesterol in the blood and the incidence of human cardiovascular diseases.. Chapter 29, . Stryer. Short Course. Lipid anabolism. Triacylglyderides. Membrane components. Cholesterol. Regulation. Steroids. TAG Synthesis. Mainly in Liver. Packaged in chylomicrons. Cholesterol Biosynthesis. Fat and Glycerophospholipid Synthesis. 1. 2. 3. 1. 2. 3. 1. 2. 3. Phosphatidic . Acid. Glycerol-3-P. Fat (Triacylglycerol). Glycerophospholipids. Fat Breakdown. Signaling. Catalysis. Glycero. Phospho. Cholesterol is an essential lipid constituent of cell membranes. Cholesterol is a precursor of steroid hormones and of bile acids. Intermediates of cholesterol biosynthesis are required to make vitamin D and for posttranslational modification of membrane proteins. Plasma lipoproteins. Prof. Mamoun Ahram. Resources. This lecture. Lippincott’s Biochemistry, Ch. 18. Characteristics of lipoproteins. Lipoproteins function to . Solubilize and carry plasma lipids. Transport lipids to (and from) the tissues. Ray . Hreiche. (updated slides from . Mohana. . Ratnapalan. & Anna . Sher. ). (THANK YOU!!!). Learning Objectives . Explain the physiological functions of cholesterol in membrane stability.. Outline the synthesis of cholesterol from acetate.. What are lipids?. If so, how are these water insoluble molecules transported from one tissue to other through an aqueous environment?. Mark the hydrophobic and hydrophilic parts on these molecules. FA. Dr. . Haidar. F. Al-. Rubaye. . Lipids are an essential nutrient with diverse functions. Lipids, also known as fats and oils, are:. One of the 6 main groups of nutrients absorbed from the diet. A major source of energy that can be stored over long periods (body fat). differes. in their amount of inherent . metabolic (. glucocorticoid. ) . and . electrolyte regulating (. mineralocorticoid. ) . activity. . . The actions of these hormones extend to . almost every cell . Functions of Cholesterol. . a precursor of. steroid hormones. (progesterone, testosterone, . estradiol. , cortisol, etc.) . a precursor of. bile acids. . a precursor of . vitamin . D. important component of many mammalian . . of . Steroid . Hormones. Chemical Bioregulation in Physiological functions. Course No. – VPY- 609. Credit Hrs. – 3+0=3. Dr.. . Pramod. Kumar. Asstt. . Professor. Deptt. . of Veterinary Physiology. The core of a steroid is formed by three cyclohexane rings (designated as rings A, B, and C) and a cyclopentane ring (the D ring). Different steroids have different functional groups attached to this four-ring core and have various oxidation states of the rings. .