by • 24/07/2011 • Old Pattern Biology NotesComments (0)548


Enzymes are chemical compounds. They are protein in nature. They are formed in living cells. They are not consumed in a reaction but act as a catalyst as they only speed up the chemical reactions.

Types of Enzymes

There are two types of enzymes:

1. Intracellular Enzymes

2. Extracellular Enzymes

·        Intracellular Enzymes:

They work within a cell, in which they are produced.

·        Extracellular Enzymes:

Some enzymes are secreted out of the cells where they work. They are called extra cellular enzyme. Bacteria and fungi secrete such extra cellular enzymes into the medium in which they are growing. The higher organisms secrete extra cellular enzymes into the lumen of alimentary canal to act on the food.

The enzymes acting on the starch are known as Amylases; those acting on proteins are known as Proteinases, while those acting on fats are known as Lipases.

Characteristics of Enzymes

The characteristics of enzymes are as follows:

1. All enzymes are protein in nature; they can be destroyed by heating.

2. They act best within a narrow, temperature range.

3. They work efficiently in narrow range of acidity or alkalinity.

4. A particular enzyme forms the same end-product, because it acts on a particular/specific substrate.

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