MCAT® ExamBiological and Biochemical Foundations of Living SystemsEasy
A researcher is studying a specific type of cell that has a high metabolic rate and produces a large amount of ATP through aerobic respiration. Upon microscopic examination, they observe that these cells contain numerous mitochondria with extensively folded inner membranes. What is the primary functional significance of these extensive folds (cristae) in the inner mitochondrial membrane?
- ATo facilitate the diffusion of glucose into the mitochondrion
- BTo increase the volume of the mitochondrial matrix for enzyme storage
- CTo provide a larger surface area for the electron transport chain and ATP synthase
- DTo protect the mitochondrial DNA from oxidative damage
Show answer & explanationAnswer & explanation
Correct answer: C. To provide a larger surface area for the electron transport chain and ATP synthase
The cristae are extensive folds of the inner mitochondrial membrane. This folding dramatically increases the surface area available for embedding the protein complexes of the electron transport chain and ATP synthase, which are critical for efficient ATP production during aerobic respiration.
Why the other options are wrong
- A. Glucose enters the cell and is broken down into pyruvate in the cytoplasm; pyruvate then enters the mitochondrion, not glucose directly.
- B. The cristae increase surface area, not necessarily the volume of the matrix.
- D. While mitochondria have defenses against oxidative damage, the primary role of cristae is not DNA protection but maximizing ATP synthesis efficiency.
Mitochondrial Cristae Function
The cristae are folds of the inner mitochondrial membrane that significantly increase its surface area, providing more space for the electron transport chain and ATP synthase.
- Located on the inner mitochondrial membrane.
- Increase surface area.
- Host electron transport chain.
- Host ATP synthase complexes.
Memory trick: Cristae Create Countless Catalytic Sites