Question

1. How would a sudden increase in the [NADH]/[NAD+] ratio effect the operation of the Krebs Cycle? Explain.

2. Why is the citric acid cycle considered amphibolic? Explain by giving examples.

Answer 1

Ans.1

Krebs cycle is the series of chemical reaction in which aerobic organisms release energy by oxidation of acetyl CoA obtained from carbohydrates, fats, protein into ATP (adenosine triphosphate) and carbon dioxide.

the cycle is primarily regulated by the concentartion of ATP & NADH.

Sudden increase in the NADH/NAD+ ratio effects the Krebs cycle -

• Promotes phosphorylationb inhibits the key process.
• inhibits generation of key acetyl CoA by inhibiting pyruvate dehydrogenase complex.
• also inhibits oxidation process of oxaloacetate and alpha-ketoglutarate.
• inhibits isocitrate dehydrogenase by displacing NAD+

ans2.

Citric acid cycle is cosidered amphibolic pathways because it serves both catabolic abd anabolic process.

Catabolic processes of carbohydrates and fatty acids into the energy in the form of ATP.

synthesis of anabolic precursors for amino acids such as-

• oxaloacetate
• alpha- keto glutarate