Question

Which step is called a gateway step/link reaction in aerobic respiration?

• A. Glycolysis
• B. Formation of acetyl coenzyme A
• C. Citric acid formation
• D. ETS terminal oxidation

Answer 1

Answer: (B)

Formation of acetyl coenzyme A

During aerobic respiration, pyruvic acid which is formed during glycolysis enters the mitochondrial matrix. It undergoes oxidative decarboxylation to produce ${CO}_2$ and NADH. The product combines with sulfur-containing co-enzyme A to form acetyl CoA. This reaction is catalyzed by an enzyme complex pyruvate dehydrogenase. This step is called link reaction or gateway step as it links glycolysis with Krebs' cycle.$Pyruvicacid+COA+{NAD}^{+}\underset{Pyruvatedehydrogenase}{\overset{M{g}^{2+}}{\to }}AcetylCoA+{CO}_2+NADH+H^{+}$

So the correct answer is 'Formation of acetyl coenzyme A'.