Final answer:
Mitochondria are the powerhouses of the cell that produce ATP through cellular respiration in a process called oxidative phosphorylation.
Step-by-step explanation:
Mitochondria are the "powerhouses" of the cell responsible for making adenosine triphosphate (ATP), the cell's main energy-carrying molecule. ATP is synthesized through cellular respiration, which occurs in the mitochondria and uses chemical energy from glucose and other nutrients. The process of ATP synthesis in the mitochondria is called oxidative phosphorylation and involves the generation of ATP through chemiosmosis, a process that relies on a proton gradient across the mitochondrial membrane.