Why does mitochondrial inner membrane folding (cristae) increase ATP output?

Core Concept

Cristae increase the surface area of the inner mitochondrial membrane, allowing that membrane to contain more electron-transport complexes and ATP synthase molecules. Greater membrane area can therefore increase the capacity for oxidative phosphorylation when substrates are available. The mitochondrion maintains an electrochemical proton gradient across the inner membrane; it is not harvesting many independent gradients on separate cristae.