Aerobic respiration can be defined as a biological process that uses oxygen to synthesize a form of chemical energy. It is this energy that powers many of the reactions within your body, such as muscle contractions and the synthesis of other molecules. Without it life could not operate: just about every move you make is governed by aerobic respiration. The process occurs within a part of the cell known as the mitochondrion.
Chemical Reactions
The equation of aerobic respiration is expressed as chemical reactions that occur within biological systems. A chemical equation has two sides--reactants and products. The molecules initially involved in a chemical reaction are the reactants, and they yield one or more molecules known as the products. Organic systems, such as aerobic respiration, use a vast array of intermediate molecules to achieve their goal. These intermediates convert the reactants into the products, but the only molecules shown in the equation are the ones that go into the reaction and the ones that come out.
Reactants
The primary reactant in aerobic respiration is a sugar known as glucose, which is broken down in the digestive system from carbohydrates consumed in the diet. After it is absorbed in the digestive tract, glucose is transported through the blood. This is how the term "blood glucose levels" originated. High levels of glucose trigger the release of the hormone insulin to usher the sugar into the cells, where it's used in aerobic respiration. However, other nutrients such as fatty acids sometimes perform the same function as glucose. The other reactant is, of course, oxygen, but it isn't needed until the end to complete the process.
Products
There are three main products of aerobic respiration. The first is carbon dioxide, a natural waste product synthesized during the conversion of glucose to other intermediate forms. The second product is water, produced at the very end of the process by the combination of oxygen and other byproducts. Finally, aerobic respiration produces a molecule known as adenosine triphosphate, or ATP. This molecule is the end goal of aerobic respiration, the form that chemical energy takes. It contains a relatively enormous amount of energy and drives other reactions throughout your body as its initial chemical bonds are severed.
Equation
The basic equation of aerobic respiration is as follows: a single glucose molecule, when used in conjunction with six oxygen molecules, will produce six carbon dioxide molecules, six water molecules and either 36 or 38 molecules of ATP. The amount of ATP is only theoretical, and it may change, depending on some complex factors that occur during the course of aerobic respiration.
