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bunton33 bunton33
wrote...
13 years ago
One batch of isolated, purified mitochondria was placed into a pH 7.2 solution. Another batch of identical mitochondria was placed into a pH 3.2 solution. The rates of electron transport in the two batches were measured. At pH 7.2 the rate was normal, but at pH 3.2 electron transport had stopped completely. In fact, it was seen that small amounts of NADH were synthesized from NAD+ in the pH 3.2 solution. Explain how synthesis of NADH could happen under these conditions.
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wrote...
Educator
13 years ago
I don't think this question was well thought of because the electron transport chain uses NADH, but does not produce it. It can't be glycolysis because we only have mitochondria - glycolysis occurs in the cytoplasm. The only thing that is left is the citric acid cycle which occurs inside the mitochondria because the citric acid cycle produces NADH from free-floating NAD+ molecules via specific enzymes. Since NADH is the reduced version of NAD+, it likely obtained its hydrogen (H+) ions from the high acidic medium in which the mitochodria were placed into: high acid = lots of H+.

What are your thoughts?
bunton33 Author
wrote...
13 years ago
i was wondering the same thing. yes i thought that the acidic 3.2ph having H protons would make sense for the NADH whereas the 7.2ph basic would have hydroxide ions. Thanks again!
bunton33 Author
wrote...
13 years ago
why does it occur in the basic solution?
wrote...
Educator
13 years ago
A better question would be, why wouldn't it occur in a basic solution?
bunton33 Author
wrote...
13 years ago
thats what i meant sorry. it is because of the hydroxide ions?
wrote...
Educator
13 years ago
The reaction still occurs because there is still hydrogen ions in a basic solution, but very little (unless you are at a pH of 14).
wrote...
13 years ago
Recall that electron transport produces an electrochemical gradient of H+ regardless.
B.Sc. (Biology)
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