IMED1003 Study Guide - Final Guide: Biotin, Carboxylation, Membrane Transport Protein
IMED1003 Final Revision Notes 5
3 Stages of FA Synthesis:!
1. Acetyl CoA transport!
2. Acetyl CoA activation!
3. Consecutive 2C addition!
Transport protein: (usefulness is FA Synthesis)!
-Allows citrate/pyruvate to enter mitochondria <-> cytosol!
-Acetyl CoA (excess from what we eat) enters this pathway!
-Citrate: instead of entering TCA cycle, goes into cytosol!
-Citrate -> acetyl CoA (enzyme: citrate lyase)!
-forming oxaloacetate as well!
-Oxaloacetate REDUCTION to malate (with input of NADH)!
Essential Fatty Acid:!
-Essential FA!
-FA contains double bonds close to methyl end of FA !
-(eg. Fish oil, has omega fats)!
-Essential: need to come from diet, can’t be made in the body!
Acetyl CoA Transport:!
-Transport: FA synthesis in cytosol!
-Most acetyl CoA in mitochondria!
-Difficult to get across cell surface membrane!
-Thus need transport system: mitochondria -> cytoplasm!
Acetyl CoA Activation: !
-To enable start of building FA!
Consecutive 2C Addition:!
-Building FA chain!
Fatty Acid Synthesis Overall:!
-8 ATP!!!!
-Cleavage and transport cycle 8 times in total -> 8 Acetyl CoA -> 8 ATP is used 1
palmitate (16C FA chain)!
-Citrate INHIBITS PFK!
-Hence = glycolysis slows down during FA synthesis!
-When we have citrate in cytosol, indicate that cell has lots of energy, thus glycolysis
slows down!
Malonyl CoA Formation:!
-When carboxyl group is added, ATP -> ADP + Pi!
Document Summary
3 stages of fa synthesis: acetyl coa transport, acetyl coa activation, consecutive 2c addition. Allows citrate/pyruvate to enter mitochondria cytosol. Acetyl coa (excess from what we eat) enters this pathway. Citrate: instead of entering tca cycle, goes into cytosol. Citrate -> acetyl coa (enzyme: citrate lyase) Oxaloacetate reduction to malate (with input of nadh) Fa contains double bonds close to methyl end of fa. Essential: need to come from diet, can"t be made in the body. Di cult to get across cell surface membrane. Thus need transport system: mitochondria -> cytoplasm. Cleavage and transport cycle 8 times in total -> 8 acetyl coa -> 8 atp is used 1 palmitate (16c fa chain) Hence = glycolysis slows down during fa synthesis. When we have citrate in cytosol, indicate that cell has lots of energy, thus glycolysis slows down. When carboxyl group is added, atp -> adp + pi. Biotin carrier protein binds to biotin (yellow box)
