Cell membrane is defined as the outer most covering of the cell which encloses all the cell components and give a defined volume, shape to the cell. It is also termed as plasma membrane. In plants it lies below the cell wall while in animals it is the outer most cover. This cell membrane has diverse functions in day to day life and also all the important stages the cell goes through starting from cell birth, reproduction and even death. The functions of cell membrane and its structure are quite interesting and worth study.
Cell membrane structure:
The cell membrane structure is complex, rigid, robust and also very effectively designed for diverse roles.
It is a lipid bi-layer with proteins in between. It is made of glycolipids (i.e carbohydrate and lipid combination) and glycoproteins (i.e. carbohydrate and protein combination).
Glycoproteins in cell membrane contribute to its rigidity while the lipid bilayer of cell membrane impart smoothness, softness elasticity and permeability.
Check out the video below for visual demonstration on cell membrane structure.
Cell membrane functions : The main function of cell membrane is to keep up the natural environment of the cell intact and maintain homeostasis.
Other function include.
a) Acts as a selective barrier to control the transport of selective substances into and also outside the cell.
b) Helps in absorption of nutrients & oxygen from external supply like blood or plasma.
c) Helps in excretion of waste from cell into blood or plasma.
d) Receptor proteins in cell membrane surface act as targets for drug, hormone to produce their action.
e) Plays an important role in cell division by initiating the cleavage process.
f) In some single cell organisms, cell membrane plays a prominent role in movement, ingestion, excretion etc.
g) It helps maintain cell volume by osmosis, excytosis and also give defined shape and size to the cell.
what is main difference between plant & animal cell
Hi mohammad asim!
Plant cells are harder while animal cell are physically smooth due to presence of an external cell wall which adds to rigidity.
Plant cells have different cellular constituents like crystal of calcium etc and also chloroplasts (photosynthesis)
Plant cells are non-movable while animal cells can change their shape and also some are movable like WBC, RBC etc. Some of them even engulf other particles.
Even certain enzymes, hormones involved in plant and animal physiology are different. For example growth hormone in plants is Auxin, gibberlins while in animals it is somatotrophin etc.
Even they have different constituents like cellulose etc which are absent in animal cell.
And centro-some is thought to be found only in animals cell while absent in plant cell.
Hope this helps..