BIOC 3300 Lecture 15: BIOC3300 Lecture 15

• School: Dalhousie University
• Department: Biochem & Molecular Biology
• Course: BIOC 3300
• Professor: Cathy Too

Document Summary

Forms cholesterol-rich, lateral membrane domains with sphingolipids: very small and highly dynamic. Precursor of steroid hormones, vitamin d, bile acids. Not used for energy production (not broken down) Sources and uses of cholesterol: sources: diet, de novo biosynthesis, uses: cell membranes, excretion, bile acids, steroid hormones. All carbons in cholesterol are derived from acetate. Acetyl-coa is generated in mitochondrial matrix precursor for energy storage or generation. Energy surplus = acetyl-coa to synthetic reactions; energy demand = acetyl-coa to. Tca: cytosol: acetyl-coa cholesterol or fatty acids, acetyl-coa is indirectly transported into cytosol by citrate lyase/tricarboxylate transport system (requires atp, mitochondrion: acetyl-coa tca oxphos atp. Acetyl-coa hmg-coa mevalonate: hmg-coa reductase reaction is main regulatory step, first committed step in the mevalonate pathway, uses nadph. Mevalonate is phosphorylated and decarboxylated: energy-costly activation by pyrophosphorylation. Six isoprene unites condense to form squalene: first committed step of cholesterol biosynthesis, molecules containing isoprene units: ubiquinone, heme a, retinol.