Question

Acetyl CoA forms a 6-C compound after combining with
A. Malic acid
B. Citric acid
C. Succinic acid
D. Oxaloacetic acid

Answer 1

Hint: Acetyl-CoA plays an important role in metabolism as it intersects with many of the metabolic pathways and transformations. Its main function is to deliver the acetyl group to the Krebs cycle which will later oxidize for energy production.

Complete step by step answer: a. Malic acid - It is an organic dicarboxylic acid compound made by all living organisms and it gives a sour taste to fruits and is also used as food additives. Malic acid has two stereoisomeric forms, but only one form exists naturally. The esters of malic acids are called as malate’s and this malate’s anion is an intermediate in the citric acid cycle.
b. Citric acid - This acid is formed by the condensation of acetyl CoA and oxaloacetate in the presence of citrate synthase. This enzyme is extensively found in mitochondria.
c. Succinic acid - This acid is obtained from amber distillation and is known as the spirit of ambers. Industrially the succinic acid is formed by the hydrogenation of maleic acid.
d. Oxaloacetate - Acetyl CoA (3 carbon compound) formed during glycolysis combines with the oxaloacetate (4 carbon compound) of the Kreb’s cycle to form citrate. This reaction is aldol condensation which is then followed by the hydrolysis and this reaction is catalysed by citrate synthase.
Hence, the correct answer is option D.

Note: Pyruvic acid is converted into Acetyl CoA which is a two-carbon compound by the link reaction which occurs through the pyruvate dehydrogenase complex and enter the second pathway of the cellular reactions where the most numbers of ATP’s are synthesized.