The Biology Project: Biochemistry

Metabolism Problem Set

Problem 5: Effect of pH on Mitochondria

If you isolate mitochondria and place them in buffer with a low pH they begin to manufacture ATP. Why?

A. Low pH increases the concentration of base causing mitochondria to pump out H+ to the inter membrane space leading to ATP production.
B. The high external acid concentration causes an increase in H+ in the inter membrane space leading to increased ATP production by ATP synthetase.
Mitochondrial production of ATP requires a concentration gradient of H+ with a high concentration at the inter membrane space and a low concentration in the matrix. The inner membrane is impermeable to H+, but the outer membrane of the mitochondria will allow H+ to pass through. Thus, placing mitochondria in a low pH buffer produces a H+ gradient that can generate ATP through ATP synthetase.
C. Low pH increases the acid concentration in the mitochondrial matrix, a condition that normally causes ATP production.
D. Low pH increases the OH- concentration in the matrix resulting in ATP production by ATP synthetase.

The Biology Project
University of Arizona
Tuesday, August 20, 1996
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