Cell Structure (Cell Membrane)

  Cell Structure

Cell Membrane

Cell membrane is also known as PLASMA MEMBRANE.

PLASMA: 

it is the protoplasm (the living matter of a cell i-e CYTOPLASM, NUCLEUS etc).

PROTOPLAST:

it is the living matter of the individual cells.

DEFINITION: 

 it is the outermost layer that surrounds all the living matter of animal cells while in Plants, Fungi as well as in Bacterial cells it lies inner to the cell wall.

CHEMICAL COMPOSITION:

It is mainly composed of

1)       LIPID (with phosphate).

2)      PROTEINS (it is the major component or portion).

STRUCTURE OF CELL MEMBRANE

Different models have been given, but due to recent advancement in microscopy or cytology. The most acceptable model have been given by

SINGER AND NICHOLSON In 1972

This model is known’s “FLUID MOSAIC MODEL OR LIPID BILAYER MODEL OF SINGER AND NICHOLSON”

MOSAIC: 

it means irregular pattern.

PROPERTIES AND IMPORTANCE OF CELL MEMBRANE:

1)      It is selectively permeable membrane.

2)      It is differential permeable (because an antigen is present on the surface).

3)      ENDO-CYTOSIS i-e inside the cytoplasm

·         Phagocytosis (on solid particles)

·         Pinocytosis (liquids)

4)      EXO-CYTOSIS i-e outside the cell

Waste products are packed in the form of vesicles (packed by Golgi bodies) and get outside the cell.

5)      ANTIGEN: The antigen present on the surface of cell membrane,

·         Produce immunity.

·         It works like an identity card.

6)      It also helps in IONS REGULATION i-e ions cannot pass through it, but they are passed out through special pores.