IMED1003 Lecture Notes - Lecture 7: Endergonic Reaction, Aconitase, Ketogenic Diet
IMED1003: TCA Cycle Lecture Notes
Learning outcomes:
-Understand the reaction catalysed by PDH & its regulation.!
-Describe the reactions of the TCA cycle, where they occur within the cell and the
regulation of the cycle.
-Know structure of pyruvate & acetyl group of Acetyl CoA.!
-Understand energy yield of glucose catabolism. Know the pathway of glycogen
breakdown.!
-Appreciate the action of arsenic as a poison.
Overview:
-Glycolysis occurs in the cytosol!
-Process of glycolysis is to: convert GLUCOSE to PYRUVATE!
-It is symport process = bring pyruvate from CYTOSOL to MITOCHONDRIA for 2
processes!
1. Pyruvate oxidation!
-Where pyruvate -> acetyl CoA + NADH!
-NOTE: this is not part of TCA cycle!
2. TCA cycle!
Acetyl CoA:
-It is a “central intermediate”!
-Pivotal molecule in metabolism!
-Because metabolism of CHO, fats and proteins all produce
acetyl CoA as intermediate !
Formation of Acetyl CoA:
-From PYRUVATE -> ACETYL CoA!
-It is irreversible!
-Formation is called: oxidative decarboxylation !
-= (removal of CO2 in presence of O2)!
-Several enzymes catalyse this reaction!
-work SEQUENTIALLY !
-= (multi-enzyme complex)!
-5 reactions!! !
Oxidative Decarboxylation:
-Final products: NAD+, CO2, Acetyl CoA!
-The oxidation (oxidative decarboxylation) of Pyruvate to Acetyl-CoA is the irreversible
route from Glycolysis to TCA Cycle!
-Occurs in the mitochondria!
-Important enzyme = Pyruvate dehydrogenase PDH!
Document Summary
Understand the reaction catalysed by pdh & its regulation. Describe the reactions of the tca cycle, where they occur within the cell and the regulation of the cycle. Know structure of pyruvate & acetyl group of acetyl coa. Appreciate the action of arsenic as a poison. Process of glycolysis is to: convert glucose to pyruvate. It is symport process = bring pyruvate from cytosol to mitochondria for 2 processes: pyruvate oxidation. Where pyruvate -> acetyl coa + nadh. Note: this is not part of tca cycle: tca cycle. Because metabolism of cho, fats and proteins all produce acetyl coa as intermediate. = (removal of co2 in presence of o2) The oxidation (oxidative decarboxylation) of pyruvate to acetyl-coa is the irreversible route from glycolysis to tca cycle. = nadh, acetyl coa, atp inhibits the activity of pdh. = pyruvate, adp activate the activity of pdh. 4c oxaloacetate + 2c acetyl coa -6c citrate. When citrate synthase bind oxaloacetate, changes shape.
