[Campbell Biology P.223] The inner mitochondrial membrane's extensive folding into cristae i... | Practice Question

The inner mitochondrial membrane's extensive folding into cristae is crucial for the efficiency of the electron transport chain. If a mitochondrion had a significantly reduced number of cristae, how would this primarily impact oxidative phosphorylation?

  • A: It would increase the rate of glycolysis in the cytoplasm to compensate for reduced ATP.
  • B: The decreased surface area would limit the number of electron transport chain components, reducing ATP synthesis.
  • C: It would enhance the diffusion of oxygen into the mitochondrion, speeding up the electron transport chain.
  • D: Substrate-level phosphorylation would increase to make up for the lack of space for the electron transport chain.

Explanation

The text explicitly states that 'The folding of the inner membrane to form cristae increases its surface area, providing space for thousands of copies of each component of the electron transport chain in a mitochondrion. Structure fits function: The infolded membrane with its concentration of electron carrier molecules is well-suited for the series of sequential redox reactions that take place along the electron transport chain.' A reduced number of cristae would mean less surface area, thus fewer electron transport chain components and lower capacity for ATP synthesis.