How does cellular respiration work?

Cellular respiration is the process by which living cells break down glucose molecules and release energy. In this process, glucose (C6H12O6) reacts with oxygen (O2) to form carbon dioxide (CO2) and water (H2O), releasing energy in the form of ATP. Cellular respiration is an aerobic process as oxygen is an essential component. 

Cellular respiration occurs in four stages. 

1. Glycolysis - In this first stage, the 6-carbon glucose molecule is broken down into two 3-carbon compounds called pyruvates and 2 ATP molecules. 
2. Pyruvate oxidation – The pyruvate molecules undergo oxidation and dehydrogenation to produce 3 ATP molecules, acetyl Co-A and CO2. 
3. Kreb’s cycle or citric acid cycle – Acetyl CoA is oxidized to produce ATP, carbon dioxide and water. 
4. Oxidative phosphorylation or electron transport chain – Electrons generated in the earlier states are transferred to oxygen and energy is released in the form of ATP.