Enzymes are Biological Catalysts

Catalyst

Catalyst: It is a substance that speeds up a chemical reaction without itself being chemically changed at the end of the reaction.

Enzymes

Enzymes: They are biological catalysts made of protein which speed up the rate of chemical reactions by lowering the activation energy required to start the reaction without being chemically changed at the end of the reaction.

Activation energy: It is the energy needed to start a chemical reaction.

What reactions do enzymes catalyse?

Digestion

• Some food molecules are large and insoluble in water. These molecules cannot diffuse across the cell membrane. They have to be converted or digested into smaller, simpler molecules in order to do so.

Building up of complex substances

• Also known as anabolic reactions. For example, building proteins from amino acids.

Break down of complex substances

• Also known as catabolic reactions. For example, breakdown of glucose during respiration.