The cell membrane is composed of lipids that are arranged in a bilayer. The lipids are arranged within the membrane with the polar head towards the outer sides and the hydrophobic tails towards the inner part. This ensures that the nonpolar tail of saturated hydrocarbons is protected from the aqueous environment . The lipid component the membrane mainly consists of phosphoglycerides. The biochemical investigation clearly revealed that the cell membranes also possess protein and carbohydrate. The ration of protein and lipid varies considerably in different cell types. The membrane proteins can be classified as integral or peripheral. Peripheral proteins lie on the surface of membrane while the integral proteins are partially or totally buried in the membrane.The widely accepted Fluid mosaic model of cell membrane was proposed by Singer and Nicolson. According, to this the quasi-fluid nature of lipid enables lateral movement of proteins within the overall bilayer. This ability to move within the membrane is measure as its fluidity.
The fluid nature of the membrane is important from the point of view of functions like cell growth, formation of intercellular junctions, secretion, endocytosis, cell division etc.
1.Now lets draw Plasma membrane
2.Draw two parallel curves as shown.
Put a integral protein in the middle as shown.
3.Draw Lipid heads along the two curves after erasing them.
4.Now draw lipid tails as shown.
5.Now draw Mosaic of lipid heads as shown.
6. Erase out few lipids and draw an integral protein as shown.
7. Now draw sugar molecules on proteins and few of lipid heads and label the parts as shown in first diagram.