Biochem Ch. 8 Q7 (p. 186)

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Biochem Ch. 8 Q7 (p. 186)

Post by shivb14 » Fri Jun 07, 2019 6:19 pm

Hello! This question relates to the total amount of ATP produced by glucose metabolism. The explanation says that "Aerobic cell respiration produces 36 ATP/glucose consumed," however, the content review from this same chapter states that complete metabolism of one glucose molecule yields 30 ATP, and that higher numbers are an overestimation (p. 181). Which number is correct?
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Re: Biochem Ch. 8 Q7 (p. 186)

Post by NS_Tutor_Mathias » Sat Jun 08, 2019 3:50 pm

For the MCAT, there is no passage-independent number that is authoritative. The yield will depend on the organism in question, the reaction environment and probably to no small degree on the procedure used to arrive at such a number. 30 is probably closer to the truth for humans, mammals and most vertebrates - but don't necessarily take that to the bank. What I can say is that it is extremely unlikely you would be asked whether the ATP output from aerobic respiration is 30, 32 or 36 ATP. That is very far away from how the MCAT tests content knowledge.

What you do want is a definitive understanding of what is produced in each step of the aerobic respiration pathway, whether glycolysis, decarboxylation of pyruvate, the Krebs cycle or the ETC. And be familiar with how many electrons an electon carrier provides, the oxidized and reduced forms of those carriers and how many protons they can contribute to pumping across the inner membrane under physiological conditions, as well as how many H+ it takes to let ATP synthase phosphorylate ADP to ATP.
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