TYPES
E.R. consists of two types - 1. Rough E.R. 2. Smooth E.R.
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Rough E.R.
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Smooth E.R.
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80s ribosomes bind by their larger subunit with the help of two glycoprotein which occur on surface of Rough E.R. i.e. Ribophorin I and II
More stable
Composed of cisternae and vesicles Abundantly occurs in cells which are actively engaged in protein synthesis e.g. liver, pancreas, Goblet cells.
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Ribosomes and Ribophorins absent
Less stable
Composed of tubules.
Abundantly occur in cells concerned with glycogen and Lipid metabolism. e.g. Adipose tissue, Interstitial
cells, Muscles, Glycogen storing liver
cells, and adrenal cortex
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Maximum number of Rough E.R. present in cells of (according to priority) -
(1) Fibroblast (whose function is fibre or protein synthesis)
(2) Plasma cell (whose function is to form antibodies which consists of protein)
(3) Pancreatic cell (form enzymes consists of proteins)
Maximum number of Smooth E.R. present in cell of (according to priority) -
(1) Interstitial cells (Leyding cells) - found in testis - functions is to secrete testosterone (male hormone, steroid nature) consists of lipids.
(2) Cells of adrenal cortex - synthesis steroid hormones. (3) Muscle fibre - glycogen (carbohydrate) synthesis.