Respiration

Respiration is the essential metabolic process whereby energy is created in the form of ATP.  There are two types of respiration, aerobic respiration and anaerobic respiration.  In aerobic respiration, there is a reaction between oxygen and glucose, resulting in the generation of 38 ATP, with carbon dioxide and water being produced as waste products.  There are a number of steps in this process, which involve a series of complex reactions.  Anaerobic respiration is the process whereby ATP is generated in the absence of oxygen.  Glucose is broken down into 2ATP and lactic acid as a waste product.
Aerobic respiration goes through complex stages (phases) in the next order:

1. Glycolysis: Where one glucose molecule (6-Carbon molecule), is transformed to two pyruvate molecules (3-Carbon molecules), and four ATP molecules.
2. Link Reaction: One pyruvate molecule is changed to one acetyl-CoA molecule (2-Carbon molecule) by releasing one carbon atom in the form of carbon dioxide.
3. Krebs Cycle: Also called the TCA (tricarboxylic acid) Cycle, occurs twice for one glucose molecule (because each glucose molecule is split into two pyruvates which produce one Acetyl-CoA each) producing: 2 ATP molecules, six NADH molecules, two FADH₂ Molecules and four CO₂ molecules 
4. Electron transport chain: Where electrons pass from one carrier to the other, with O₂ as the last carrier, producing 32 ATP molecules, using ATP_synthase.