Pyruvate Oxidtion & Krebs Cycle

the absolute basics

What happens during pyruvate oxidation?

Pyruvate enters the mitochondrial matrix. One carbon leaves as CO2, NAD+ is reduced to NADH, and CoA joins the remaining 2-carbon molecule to form acetyl-CoA.

What are the inputs and outputs of pyruvate oxidation?

Inputs: 2 pyruvate (3C each), 2 NAD+, 2 CoA. Outputs: 2 acetyl-CoA (2C each), 2 CO2 (1C each), 2 NADH.

What is oxidized and what is reduced during pyruvate oxidation?

Pyruvate is oxidized (loses electrons). NAD+ is reduced (gains electrons and becomes NADH).

What is the Krebs cycle?

Also called the citric acid cycle. Occurs in the mitochondrial matrix. An 8-step pathway, each step catalyzed by a specific enzyme. Involves stepwise catabolism of a 6-carbon citrate molecule.

Why does the Krebs cycle stay at 4 carbons?

The 4-carbon molecule is regenerated each cycle. It combines with 2-carbon acetyl-CoA to form 6-carbon citrate.

What are the outputs of ONE turn of the Krebs cycle?

2 CO2, 3 NADH, 1 FADH2, and 1 ATP.

How many times does the Krebs cycle occur per glucose molecule?

Twice, because one glucose produces two pyruvate and therefore two acetyl-CoA.

What are the total outputs of the Krebs cycle per glucose?

4 CO2, 6 NADH, 2 FADH2, and 2 ATP.

What is the purpose of NADH and FADH2?

They carry high-energy electrons to the electron transport chain, where they help produce ATP.