S phase is the DNA synthesis phase. During this portion of the cell cycle, the cell replicates its entire complement of DNA. It also forms the centrosome, which is the microtubule-organizing center that will eventually help the cell pull apart the DNA that will be divided between daughter cells.
Cell regulation is conducted by special proteins. These special
proteins are enzymes which help in the regulation of bodily function. They hasten
the chemical reaction such as pepsin. Pepsin is a protein that helps in the
digestion of food in the body.