BiochemistryLesson 1 of 1 in the course Cellular Respiration

Pyruvate Oxidation and Citric Acid Cycle: Reactions and Products

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

This lesson explains how pyruvate, the product of glycolysis, is prepared to enter the citric acid cycle. In aerobic respiration, pyruvate is transported into the mitochondrial matrix and converted into acetyl CoA. This transition releases carbon dioxide and captures energy in NADH.

When oxygen is available, aerobic respiration can continue beyond glycolysis. In eukaryotic cells, pyruvate produced in the cytoplasm is transported into the mitochondrion. Pyruvate oxidation occurs in the mitochondrial matrix, before the citric acid cycle.

All flashcards

What is the overall product set from pyruvate oxidation of one pyruvate?
One carbon dioxide, one NADH, and one acetyl CoA.
What does NAD⁺ do during pyruvate oxidation?
It accepts electrons released as the two-carbon fragment is oxidized, becoming NADH.
What is the role of acetyl CoA in the citric acid cycle?
It delivers a two-carbon acetyl group to the cycle.
What are the products of one turn of the citric acid cycle?
Three NADH, one FADH₂, two CO₂, and one GTP or ATP.
Why is the citric acid cycle described as amphibolic?
It functions in both catabolism and biosynthesis.

Quiz questions

  1. Where does pyruvate oxidation occur in eukaryotic cells?Answer: In the mitochondrial matrix.
  2. When one acetyl group enters the citric acid cycle, what forms when it combines with oxaloacetate?Answer: Six-carbon citrate.
  3. What kind of phosphorylation produces GTP or ATP as succinyl CoA is converted to succinate?Answer: Substrate-level phosphorylation.
  4. Which citric acid cycle enzyme is embedded in the inner mitochondrial membrane?Answer: Succinate dehydrogenase.
  5. Why is the citric acid cycle considered aerobic although it does not directly consume oxygen?Answer: Its continued operation depends on the electron transport chain transferring electrons to oxygen.

Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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