Question

1. The citric acid cycle plays a key role in catabolism and biosynthesis. How much ATP is generated, and what compounds are generated which are used in biosynthesis and what are they used for? (7)

Answer 1

In 2 rounds of citric acid cycle this generates 6 NADH, 2 FADH2 and 2 ATP. After oxidative phosphorylation this is 24 ATP Total. And by a glucose total 38 ATP is formed, a fraction of ATP is generated by fattyacids.

Many intermediates compounds are generated during cirtric acid cycle which further used in biosynthesis i.e. most of the carbon atoms in porphyrins come from succinyl CoA, Many of the amino acids are derived from α-ketoglutarate andoxaloacetate.

The acetyl CoA cannot be transported out of the mitochondria for this the citrate is removed from CAC and transported to cytosol where it is converted to oxaloacetate and Acetyl CoA (this cytosolic acetyl CoA is used for fatty acid synthesis) by an enzyme ATP citrate lyase and then oxaloacetate returns to the mitochondria in the form of malate.

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