All living organisms use energy. Adenosine triphosphate (ATP) is the molecule that supplies most of the energy for cellular work and is the end product of cellular respiration , which is a metabolic pathway comprised of a series of steps that convert the chemical energy in glucose into the energy contained in ATP.
This tutorial will focus on the breakdown of glucose, but keep in mind that molecules can enter the pathway at various points; therefore, glucose is just one of several sugars that can be broken down during cellular respiration. The available energy in glucose (and other sugars) resides within its electrons. These electrons (along with their energy) are removed and passed to intermediate electron carriers in a step-by-step process. These intermediates (e.g., NADH) and the concept of reduction-oxidation reactions will be addressed in this tutorial. This tutorial will also cover the events that occur in a cell when oxygen or another terminal electron acceptor molecule is not available - the processes of fermentation.
The Learning Objectives for this tutorial are the by the end of the tutorial you should be able to: