Enzymes are the biological catalysts that accelerates biochemical reactions. The molecule on which an enzyme acts is called a substrate. and substrate is finally converted into a product. The study of enzymes is called Enzymology and the enzymes are known to catalyse more than 5000 reactions taking place in the cell. Most of the enzymes are made up of proteins, however some RNA molecules can also act as enzymes. There are many factors that affect the enzyme activity. These includes pH, temperature, presence of salts etc. The enzymes are most active when these conditions are kept optimum. A drastic change in pH temperature or ionic strength can decrease the enzyme activity