Where does the first stage of aerobic cellular respiration occur?

The first stage of aerobic cellular respiration occurs in the cytosol, primarily consisting of glycolysis. During glycolysis, glucose is broken down into two molecules of pyruvate, generating a small amount of ATP and NADH in the process. This stage does not require oxygen and takes place in the fluid part of the cell where various metabolic processes occur.

Following glycolysis, if oxygen is present, the pyruvate molecules subsequently enter the mitochondria for the next stages of respiration: the Krebs cycle and electron transport chain. Therefore, understanding that glycolysis occurs in the cytosol is crucial for grasping the sequence and site of biochemical processes involved in cellular respiration.