Question

What does Pyruvic acid lose at the beginning of the Krebs cycle, what does it attach to, and what is the name of that new compound?

A. It loses carbon dioxide and attaches to acetyl-CoA, forming citric acid.
B. It loses an electron and attaches to ATP, forming NADH.
C. It loses oxygen and attaches to glucose, forming pyruvate.
D. It loses water and attaches to FAD, forming FADH2.

Answer 1

Pyruvic acid loses a molecule of carbon dioxide to form acetyl-CoA, which then attaches to oxaloacetate, forming citric acid as it enters the Krebs cycle.

Step-by-step explanation:

Before the Krebs cycle begins, pyruvic acid loses a molecule of carbon dioxide and becomes a two-carbon acetyl group. This acetyl group then attaches to coenzyme A (CoA) to form acetyl-CoA. When acetyl-CoA enters the Krebs cycle, it combines with a four-carbon molecule, oxaloacetate, to form a six-carbon molecule called citric acid. The correct answer to the question is: A. It loses carbon dioxide and attaches to acetyl-CoA, forming citric acid.