Question

Acetyl CoA connects

• A. EMP and Glycolysis
• B. Calvin cycle and EMP
• C. Glycolysis and Krebs cycle
• D. Krebs cycle and ETS

Answer 1

Answer: (C)

Glycolysis and Krebs cycle

The transition reaction connects glycolysis to Krebs cycle by a process called oxidative decarboxylation. Pyruvate (3-carbon molecule) from glycolysis is converted into acetyl-Coenzyme A (2-carbon molecule) and CO${}_2$. When the two pyruvates undergo oxidative decarboxylation, two molecules of NAD${}^{+}$ become reduced to 2NADH + 2H${}^{+}$ which carry protons and electrons to the electron transport chain to generate additional ATP by oxidative phosphorylation. The two molecules of acetyl-CoA can now enter the citric acid cycle.

The overall reaction for the transition reaction is:

2 pyruvate + 2 NAD${}^{+}$ + 2 Coenzyme A → 2 acetyl-CoA + 2 NADH + 2 H${}^{+}$ + 2 CO${}_2$

So, the correct option is 'Glycolysis and Krebs cycle'.