Where does dissimilation take place?

Dissimilation is a reaction of energy metabolism, that is, a set of reactions of decomposition of complex molecules of organic substances to simpler ones with the release of energy. Dissimilation reactions are carried out in three stages:
1) preparatory – takes place in the digestive system, all energy is dissipated in the form of heat;
2) anoxic (glycolysis) – takes place in the cytoplasm of cells, ATP (40%) and heat (60%) are synthesized;
3) oxygen (respiration) – passes in the mitochondria, ATP (55%) and heat (45%) are synthesized.