Cristae are the inner membrane folds found in the mitochondria, the energy-producing organelles in cells. These folds increase the surface area available for biochemical reactions, particularly those involved in cellular respiration. The more cristae present, the more energy a cell can produce. The structure of cristae is essential for the function of ATP synthase, an enzyme that generates adenosine triphosphate (ATP), the primary energy currency of the cell. By maximizing the area for these reactions, cristae play a crucial role in maintaining the energy needs of the cell and supporting various cellular processes.