We are going to do a very brief overview (believe it or not) of some very complex chemical pathways. You are not responsible for knowing the chemical structures of any of the compounds or the step by step details of the reactions. Let the review questions be your guide to the depth of understanding required.
The nucleotide ATP (adenosine triphosphate) is the prime energy carrier for all cells, both autotrophic and heterotrophic.
All energy-releasing pathways whether aerobic (requiring oxygen) or anaerobic (not requiring oxygen) begin with a pathway called glycolysis, which occurs in the cytoplasm (cytosol).
Fermentation (anaerobic) pathways and anaerobic electron transport can release small quantities of energy without the use of oxygen. Fermentation produces a net yield of two ATP.
Aerobic respiration is the main energy-releasing pathway leading to ATP formation. It occurs in the mitochondria. Aerobic respiration yields thirty-six ATP.
In plain English, one molecule of glucose plus six molecules of oxygen are broken down into six molecules of carbon dioxide and six molecules of water.
In a future lecture you will see that the equation for aerobic respiration is essentially the reverse of the equation for photosynthesis, which is how plants make food:
Aerobic Respiration consists of the following three pathways:
The end products of the Krebs Cycle in turn feed into the electron transport system, also located in the mitochondria.
Three series of reactions are required for aerobic respiration: