Question

Classification of protein according to their biological functions

Answer 1

They are coded for by our genes and form the basis of living tissues. They also play a central role in biological processes. For example, proteins catalyse reactions in our bodies, transport molecules such as oxygen, keep us healthy as part of the immune system and transmit messages from cell to cell.

Answer 2

Answer:

★ Proteins:

Proteins are the long chain polymers of amino acids and possess high molecular weight. They contain C, H, O and N. The presence of N distinguishes them from carbohydrates and lipids. Some proteins contain sulphur, while few proteins contain phosphorus also. Cells contain a large number of proteins.

★ Biological functions of proteins:

The biological importance of proteins is as follows:

i. Membrane proteins: Cell membrane consists of proteins and lipids. All membrane bound cell organelles have lipids and proteins in their membranes.

ii. Enzymes: All enzymes are proteins. Enzymes may contain some other non-protein part also along with protein. e.g. Amylase.

iii. Hormones: Hormones are proteins. They play an important role in the regulation of metabolic reactions in the body, e.g. Insulin, thyroxine.

iv. Transport protein: Haemoglobin which is present in R.B.C. of man is a type of protein. It is useful for transportation of oxygen.

v. Contractile protein: Muscle fibres consist of proteins, which help in contraction. e.g. Myosin.

iv. Structural protein: These proteins form parts of cells or tissues. e.g. Keratin is present in hair and skin, while elastin is present in connective tissue.

vii. Defensive proteins: Useful for the protection of body. e.g. Immunoglobin, thrombin for clotting of blood.