Question

What is an enzyme and what does it do?

Answer 1

Enzymes are protein which increases the rate of biological reaction without itself being changed. So They are often called boicatalyst. Virtually all cellular reactions or processes are mediated by enzymes.

Now what enzyme dose-

It increases the rate of a reaction by lowering the activation energy. So reactants can achieve the transition state easily and the reaction speed up.

In a reaction reactants or substrate gives product. This transformation is mediated by enzymes. There is an energy barrier or energy hill between reactants and products. To get product that energy hill must be achieved. Enzymes activate substrate by covalent modification of the substrate by providing an alternative lower energy reaction path. This activation releases an energy called binding energy. This binding energy lowers the activation energy and reaction proceeds.