The cell membrane has several key functions: 1. It compartmentalizes the cell by separating the internal components from the external environment and allowing organelles to maintain their own environments. 2. It allows for the transfer of materials and information between organelles and between cells via selective permeability and transport proteins. 3. It acts as a site for many cellular reactions like ATP synthesis, and contains receptors for hormones that trigger intracellular responses.

1. Attiya Bano
Functions of cell membrane

3. Cell membrane
The semipermeable membrane surrounding the cytoplasm of a
cell.
Composition
It is composed of four different types of molecules:
Phospholipids
Cholesterol
Proteins
Carbohydrates

4.  structure

5.  Functions of Cell Membranes:
 1. Compartmentalization:
 The major function of cellular membranes is
compartmentalization. As plasma membranes they
separate the cells from their external environment. As
organelle coverings, they allow the cell organelles to
maintain their identity, specific internal environment
and functional individuality.

6.  2. Transfer of material:
 The membranes allow the flow of materials and
information between different organelles of the same
cell as well as between one cell and another.
 3. Source of Organic connection:
 As plasmodesmata and gap junctions, the bio
membranes provide organic connections between
adjacent cells.

7.  4. Selective permeability:
 Plasma membranes as well as other membranes of
the organelles have selective permeability, that is, they
allow only selected substances to pass inwardly . The
membranes are impermeable to others.
 others.


8.  6. Reorganization centers:
 Plasma membrane possesses specific substances at its
surface which function as recognition Centre and points of
attachments
 7. As antigen specificity:
 Substances attached to cell membrane determine antigen
specificity. Glycophorins present on the surface of
erythrocytes function as antigen determinants.
Histocompatibility antigens signify whether a foreign cell or
tissue should be incorporated or rejected.

9.  8.As a hormone receptor:
 Cell membrane has receptors for certain hormones. The
hormone combines with its particular receptors and either
changes membrane permeability or activates enzyme
adenylatecyclase to produce cyclic AMP from ATP. AMP then
triggers a set of enzymes to perform a particular function.
 9. Center of many reaction:
 Cell membranes contain enzymes for performing certain
reaction on their surface, e.g., ATP-ase (for ATP synthesis and
release of energy from ATP), phosphatases, esterases etc.

10.  9. Perform active transport:
 Membranes have carrier proteins for active
transport.

11.  11. Work as an electron transport chain:
 Certain cell membranes (e.g. plasma membrane in
bacteria, thylakoid membranes of chloroplasts, inner
mitochondrial membrane) possess electron transport
systems.
 12. Endocytosis:
 Membrane enfolds are used for bulk intake of
materials by endocytosis