Respiration
The source of the energy required to regenerate ATP is the chemical energy stored in food (e.g. glucose). The cellular process of releasing energy from food through a series of enzyme-controlled reactions is called respirationThe chemical change that takes place inside living cells, which uses glucose and oxygen to release the energy that organisms need to live. Carbon dioxide is a by-product of respiration.. Some of the energy released is used to produce ATP. Some of the energy released is lost as heat.
Mammals need to release heat energy from food to keep their body temperature close to the optimum operating temperature for their enzymes.
There are two types of respiration. Aerobic respiration occurs if oxygen is present in the cell. fermentationA term for respiration in the absence of oxygen. occurs if oxygen is absent.
Aerobic respiration
The following is a summary word equation for aerobic respiration.
\(glucose+oxygen\to{carbon~dioxide}+water+energy\)
In reality the process of respiration consists of a series of reactions that can be divided into two stages. Stage one takes place in the cytoplasm and stage two occurs in the mitochondria of animal, plant and fungal cells.