36.
Give an illustrated account of the detailed structure and functions of the plasma membrane.
Answer:
(a) structure
Plasma membrane made up of two layers are composed of phospholipid .The hydrophilic heads of the phospholipids are in contact with water and extracellular fluid in the outer layer and the inner layer in in contact with the cytoplasm.The hydrophobic tails face each other in the middle of the bilayer.The protein molecules float about in phospholipid bilayer forming a mosaic pattern.There are two types of membrane protein which are globular protein.Intrinsic protein are the protein that are fully or partially embedded in the phospholipid bilayer. Extrinsic protein are the proteins that are found floating on the external or internal surface of the plasma membrane.Some of the membrane protein and phospholipid have short ,branched carbohydrate chains ,forming glycoprotein and glycolipid.Lipids such as cholesterol are inserted among phospholipid molecules.
(b) function
It is the protective membrane surrounds the outside of both Eukaryotic and Prokaryotic cells.It is made up of a double layer of phospholipid and controls the movement of various substances into and out of the cell.It also allows cell identification.It seperate interior of a cell from external environment.It is selectively permeable and amphipathic in nature.
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