What would be the ATP yield for a molecule that is catabolized to form one molecule of pyruvate in a eukaryotic cell?

Question

A.  10 ATP
B.  12.5 ATP
C.  25 ATP
D.  30 ATP
E.  11.5 ATP

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?

  Gather Content
  What do you already know about ATP yield from pyruvate during cellular respiration? What other information is related to the question?
   Choose Answer
  Do you have all the information needed to calculate the ATP yield from pyruvate?

  Reflect on Process
  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

B.  12.5 ATP

Clarify Question
What is the key concept addressed by the question?
        · The question essentially asks you to determine the ATP yield for one molecule of pyruvate in a eukaryotic cell.
What type of thinking is required?
        · You are being asked to take what you know about pyruvate and use, or apply, your knowledge to determine how many ATP can be yielded from one pyruvate molecule in a eukaryotic cell.

  Gather Content
  What do you already know about ATP yield from pyruvate during cellular respiration? What other information is related to the question?
        · Recall that cellular respiration is comprised of glycolysis, pyruvate oxidation, the Krebs cycle, and electron transport. Pyruvate is the main product of glycolysis, but is subsequently metabolized in downstream stages of cellular respiration.
        · Remember that after glycolysis, pyruvate (a 3-carbon molecule) undergoes an oxidation to form acetyl-CoA (a 2-carbon molecule) and a carbon dioxide molecule. This bond breakage also generates high-energy electrons that are captured by NAD+ to form NADH. Thus, a single pyruvate oxidation reaction produces a single NADH molecule. Acetyl-CoA then goes on to the Krebs cycle where it becomes incorporated into citrate and is systematically oxidized to oxaloacetate. Considering all the bonds that are broken during pyruvate oxidation and the Krebs cycle, how many ATP could potentially be made?
   Choose Answer
  Do you have all the information needed to calculate the ATP yield from pyruvate?
        · As we figured out earlier, pyruvate oxidation yields 1 NADH and 1 acetyl-CoA. 1 acetyl-CoA enters the Krebs cycle, it will undergo one turn which generates 3 NADH molecules and 1 FADH2 molecule. That means there are now 4 NADH and 1 FADH2 molecules total.
        · Recall that each NADH molecule can produce 2.5 ATP molecules and FADH2 can produce 1.5 ATP molecules via ATP synthase and the chemiosmotic proton gradient. So, the total ATP yield would be (4 NADH*2.5 ATP) + (1 FADH2*1.5 ATP) + 1 ATP (substrate-level phosphorylation in Krebs) = (10 ATP + 1.5 ATP + 1 ATP) which finally = 12.5 ATP.

  Reflect on Process
  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        · Answering this question correctly depended on your ability to apply what you know about pyruvate oxidation and the Krebs cycle to determine the ATP yield for a molecule that is converted into pyruvate.         · If you got the correct answer, nice job! If you got an incorrect answer, were you able to identify where NADH and FADH2 molecules were produced during pyruvate oxidation and the Krebs cycle? Were you able to accurately tally how many ATP molecules were produced from NADH and FADH2? Did you remember to add the single ATP from substrate-level phosphorylation?