What are the steps of aerobic respiration?

Aerobic respiration is a biological process that involves breaking down food glucose and converting it to cellular energy in the presence of oxygen. This enzymatic process takes place over 4 main steps, with each step occurring at a different site. 

The four steps of aerobic respiration include: 

1. Glycolysis: In this first step, glucose is converted into pyruvate in the cellular cytosol. 
2. Pyruvate Decarboxylation: The pyruvate molecule formed during glycolysis is transported into the mitochondrial matrix where it is converted into Acetyl-CoA through decarboxylation (removal of a carbon dioxide molecule). Two NADH (nicotinamide adenine dinucleotide) molecules are generated at the end of this step 
3. Krebs cycle or Citric acid cycle: The Krebs cycle includes a series of chemical reactions that result in the production of 2CO2, 1 ATP, NADH, and FADH, which are used in the last step of aerobic respiration.  
4. Electron transport system and Oxidative phosphorylation: The electron transport chain, which is a series of protein complexes embedded in the inner mitochondrial membrane, marks the fourth and final stage of aerobic respiration. NADH and FADH2 produced in the earlier steps donate the electrons that they carry to the electron transport complex (ETC). The protons move through the 4 protein complexes in the ETC, generating a proton gradient. The proton gradient powers the synthesis of ATP molecules from ADP and inorganic through the process of oxidative phosphorylation.