TNPSC VAO Zoology Study Materials In Tamil PDF Download
Function-It regulates what enters and leaves the cell (also called selective permeability). It also gives the cell shape and protection. Structure-Made up of two layers of phospholipids with proteins embedded randomly in the layers. Lipid soluble substances, like alcohol, easily pass across the membrane by dissolving in it. Lipid insoluble substances cannot pass, and water passes through protein lined pores. Function-Primarily concerned with protein synthesis and transport. Most highly developed in protein exporting cells (eg. Liver and pancreatic cells) Structure-It is a series of interconnected membranes which spread throughout the cytoplasm forming channels of flattened sacs, with ribosomes attached to them. The channels formed by the membranes transport the proteins made by the ribosomes.
Function-synthesizes and transports lipids and steroids. Some kinds of smooth E. R. Accepts, modifies, and transports proteins from the rough E. R. And still other kinds break down energy rich glycogen and fats. Structure-The smooth E. R. Is free of ribosomes so has a smooth appearance. The channels formed are similar to those formed by the rough E. R. But are tubular and are concerned with making and transporting lipids and steroids. Function-Proteins exported from the rough and smooth E. R. Are modified and enclosed in secretory or lysosomal vesicles and transported out of the cell. Structure-The golgi appear as flattened stacks of membranes. The proteins enter these membranes are modified, concentrated and packaged into small spherical membrane bound structures called vesicles