Question

Pyruvate oxidation is a critical step in the metabolism of glucose in the cell. It is an important step that links the initial breakdown of glucose in glycolysis in the cytoplasm to the Krebs cycle in the mitochondria. Which of the following is a reason pyruvate oxidation occurs in the mitochondria instead of the cytoplasm?

A) Glucose in the cytoplasm inhibits pyruvate from being oxidized.
B) ATP is required to oxidize pyruvate, and ATP is produced in the mitochondria.
C) There is no oxygen available for the cell to metabolize pyruvate in the cytoplasm.
D) NAD+ is found in the mitochondria as a by-product of the electron transport chain.

Answer 1

The correct answer is that pyruvate oxidation occurs in the mitochondria because NAD+, essential for accepting electrons during this process, is found there as a by-product of the electron transport chain.

Step-by-step explanation:

Pyruvate oxidation takes place in the mitochondria rather than in the cytoplasm. This process involves the oxidation of pyruvate to form acetyl CoA, which then enters the Krebs cycle. The correct answer is D) NAD+ is found in the mitochondria as a by-product of the electron transport chain. This is because NAD+ is required to accept electrons during the oxidation of pyruvate.

When NAD+ receives these electrons, it is transformed into NADH, which then can carry electrons into the electron transport chain for further ATP production. The mitochondria contain all the essential enzymes and cofactors needed for the oxidation of pyruvate and subsequent energy production steps.