What are the three major steps of aerobic respiration?

The three major steps of aerobic respiration are glycolysis, the Krebs cycle, and the electron transport chain.

Glycolysis is the initial step where glucose is broken down into pyruvate, generating a small amount of ATP and NADH. This process occurs in the cytoplasm and does not require oxygen.

Following glycolysis, the pyruvate molecules enter the mitochondria where they are further processed in the Krebs cycle, also known as the citric acid cycle. This cycle involves a series of reactions that produce carbon dioxide, ATP, NADH, and FADH2, which are essential for energy production and are subsequently used in the next phase.

The final step is the electron transport chain, found in the inner mitochondrial membrane. This stage uses the electrons carried by NADH and FADH2, producing a large amount of ATP through oxidative phosphorylation and releasing water as a byproduct when electrons combine with oxygen.

This sequence is critical for efficient energy production in cells utilizing oxygen, distinguishing it from processes like fermentation, which occurs in anaerobic conditions and lacks the Krebs cycle and electron transport chain. This understanding emphasizes the role of aerobic respiration in energy metabolism compared to other forms of cellular respiration.