Explain various functions of cell membrane.

Question

Explain various functions of the cell membrane.

Answer 1

Modifications of plasma membrane:

In animal cells, the plasma membrane forms certain structures to perform special functions which are as follows –
(i) The epithelial cells form finger – like processes called microvilli to provide increase surface for absorption.
(ii) It forms desmosomes between adjacent cells that consists of tono fibrils.
(iii) In some cells, it forms interdigitations.

Functions of Plasma Membrane:

1. It provides shape & size to the cells.
2. It protects the cell organelles.
3. It performs transportation of the substances which is of two types-

• Passive transport – It involves movement of the substances from their high to low concentration. It does not require energy.
• Example – Diffusion, Osmosis.
• Active transport – It involves movement of the substances against concentration gradient i.e. from low to high concentration. It takes place at the cost of energy (ATP). In this process carrier proteins (Permeases) act as carrier.

1. It helps in cell adhesion.
2. It bears respiratory enzymes in prokaryotes (e.g. bacteria)
3.  It performs endocytosis. The intake of substance with the help of plasma membrane is called as endocytosis. The intake of solid substance is termed as phagocytosis and the intake of liquid substances is called as pinocytosis.
   (vii) It performs exocytosis (expulsion of waste products from the cell).