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Acetyl-CoA catboxylase converts acetyl-CoA to Malonyl Coa in fatty acid de novo synthesis: coenzyme = biotin malic enzyme produces NADPH from malate HMG CoA reductase cholestorol de novo synthesis: converts HMG-CoA to mevalonate needs NADPH FPP used to form squalene, ubiquinone and dolichol Thiolase acetyl-CoA to acetoacyl-CoA HMG CoA synthase acetoacyl CoA to HMG CoA SREBP when cholesterol levels are high the SREBP will be inhibited from stimulating transcription of the HMG CoA reductase gene AMP Kinase will inhibit HMG CoA reductase Ubiquitin leads to to ubiquitination of HMG CoA reductase and its eventual degradation by proteosomal degradation The double-bond formation in cholesterol needs a specific enzyme (7-dehydrocholesterol-7- reductase). What is the name of the genetic defect of cholesterol synthesis related to deficiency of this enzyme? What are the clinical complications? SLOS: low IQ in survivors How is cholesterol degraded? converted into bile acids and secreted in feces 7-alpha-hydroxylase needed for bile acid synthesis: Cholelithiasis deficiency of bile salts: leads to gall stone formation Describe two actions of high levels of free cholesterol that reduce cholesterol synthesis! Discuss! inhibits HMG CoA reductase synthesis and leads to its degradation Desmolase forms pregnenolone from cholesterol STAR steroidogenic acute regulatory protein: transports free cholesterol from cytosol into mitochondria Why does the deficiency of any enzyme needed for cortisol synthesis lead to congenital adrenal hyperplasia? Explain. cortisol is not available to inhibit ACTH: thus ACTH continuously stimulates the adrenal cortex causing hyperplasia