AP BIOLOGY

Detailed explanation-1: -The three-carbon pyruvic acid molecules are converted to a two-carbon molecule attached to Coenzyme A, called acetyl CoA, via the process of pyruvate oxidation. It is the product, acetyl CoA, which enters the Krebs cycle.

Detailed explanation-2: -Answer and Explanation: The molecules that can enter the Krebs or Citric Acid cycle are Acetyl CoA. Acetyl CoA is made in an intermediate step between glycolysis and the Krebs cycle.

Detailed explanation-3: -Acetyl-CoA enters the Krebs cycle by combining with a four-carbon acid called oxaloacetic acid. The combination forms the six-carbon acid called citric acid. Citric acid undergoes a series of enzyme-catalyzed conversions. The conversions, which involve up to ten chemical reactions, are all brought about by enzymes.

Detailed explanation-4: -In the first step of the cycle, acetyl CoAstart text, C, o, A, end text combines with a four-carbon acceptor molecule, oxaloacetate, to form a six-carbon molecule called citrate.

Detailed explanation-5: -Citrate is produced in the Krebs cycle from oxaloacetate and acetyl-CoA by citrate synthase (CS). It can be exported from the mitochondria through citrate carrier (CIC). Cytosolic citrate is broken down by ACLY to oxaloacetate and acetyl-CoA. Acetyl-CoA can be used as a substrate for fatty acid synthesis.