Question

Pyruvic acid is converted into a compound before formation of oxaloacetic acid in the citric acid cycle, this compound is
A) Acetyl COA
B) Acetoacetic acid
C) Lactic acid
D) Cis aconitic acid

Answer 1

Hint:Citric acid cycle is a series of reactions that takes place in an aerobic organism by which the stored energy is released. Pyruvic acid is the end product of glycolysis.

Complete answer:
Citric acid cycle is also known as TCA cycle or Krebs cycle. It involves the oxidation of acetyl CoA which is derived from fats, carbohydrates,and protein in order to release stored energy. Let us analyze the option to find the correct answer.

>Option A: Formation of acetyl CoA is the next step after pyruvic acid. This is the link between the Krebs cycle and glycolysis as Acetyl CoA which is a 2 carbon compound combined with oxaloacetic acid (4 carbon) to give the next product called citric acid (6C). Acetyl CoA is the link between glycolysis and TCA cycle. Therefore, this is the correct option.
>Option B: Acetoacetic acid is produced in the mitochondria. It is produced from acetoacetyl CoA.Therefore, this is the incorrect option.
>Option C: Lactic acid forms the part of the Cori cycle. Cori cycle is a metabolic pathway in which lactate is produced through anaerobic glycolysis of glucose.Therefore, this is the incorrect option.
>Option D: Cis aconitic acid is an intermediate that is formed when the citric acid is converted into isocitric acid. Therefore, this is the incorrect option.

Thus, the correct answer is option (A) Acetyl COA.

Note:Citric acid cycle is initiated by Acetyl CoA. oxidation reaction removes carboxyl group from pyruvate. $NAD6^+$ accepts an electron during this to form NADH and two carbon Acetyl CoA is released when coenzyme is attached to it.