3. Some common classifications of lipids and their general biologic functions Lipid Primary Functions Fatty acids Energy sources, biosynthetic precursors Triacylglycerols Storage, transport Phosphoglycerides Membrane components Ketone bodies Energy sources Sphingolipids Membrane components Eicosanoids Modulators of physiologic activity Cholesterol Membrane component Steroid hormones Modulators of physiologic activity
37. Sphingolipidoses are inherited genetic disorders referred to as lipid storage diseases, in which there is a deficiency of an enzyme that is involved in the normal catabolism of a particular sphingolipid . This results in the intracellular accumulation of that lipid to harmful levels. Disease Lipid Accumulated Enzyme Deficiency Primary Organ Affected Niemann-Pick Sphingomyelin Sphingomyelinase Brain, liver, spleen Gaucher's Glucocerebroside -Glucosidase Brain, liver, spleen Krabbe's Galactocerebroside -Galactosidase Brain Metachromatic leukodystrophy -Sulfogalactocerebroside Sulfatide sulfatase Brain Fabry's Ceramide trihexoside -Galactosidase Kidneys Tay-Sachs Ganglioside GM 2 Hexosaminidase A Brain
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42. Vitamin D The binding of vitamin D to receptor turns on the gene responsible for the synthesis of a Ca 2+ binding protein Absence in diet, or insufficient sunlight, leads to rickets Typically vitamins are included in various foods such as bread and milk. Vitamin D 2 is added to milk and butter
52. CHYLOMICRON FORMATION Free fatty acids and monoacylglycerols are absorbed by intestinal epithelial cells. Triacylglycerols are resynthesized and packaged with other lipids and apoprotein B-48 to form chylomicrons, which are then released into the lymph system.
53. Schematic Model of Low-Density Lipoprotein. The LDL particle is approximately 22 nm (220 Å) in diameter
78. Stoichiometry of the synthesis of palmitate 8 Acetyl CoA + 7 ATP + 14 NADPH + 14 H + + H 2 O -> -> Palmitate + 7 ADP + 7P i + 8 CoASH + 14 NADP +
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86. Transfer reaction CPT - carnitine palmitoyl transferase On the outer surface of the inner mitochondrial membrane, the enzyme carnitine palmitoyl transferase I (CPT I) catalyzes the transfer of the acyl group from CoA to carnitine. The fatty acyl group is translocated across the membrane to the inner surface, where the enzyme carnitine palmitoyl transferase II (CPT II) catalyzes the transfer of the acyl group to CoA drawn from the matrix CoA pool
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91. First Three Rounds in the Degradation of Palmitate. Two-carbon units are sequentially removed from the carboxyl end of the fatty acid
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112. KETONE BODY METABOLISM Ketone bodies (i.e., acetoacetate, -hydroxybutyrate, acetone) are the preferred energy substrates of the heart, skeletal muscle, and kidney during the fasting state. If blood levels of -hydroxybutyrate and acetoacetate increase sufficiently, as they do during starvation, they also become the primary energy substrate for the brain.
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119. STEROIDS are lipids that contain four fused carbon rings that form the cyclopentanoperhydrophenanthrene steroid nucleus.
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123. HMG CoA is converted to mevalonate by HMG CoA reductase , an NADPH-dependent enzyme. This is the key regulatory site of cholesterol biosynthesis
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127. The drug lovastatin, which is used to treat hypercholesterolemia, blocks endogenous cholesterol synthesis by inhibiting HMG CoA reductase
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135. Lanosterol is converted to cholesterol by a series of reactions that result in the removal of three methyl groups and rearrangement of double bonds
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