User:Sohail bhatti Pakistan

notes on Viruses

Definition:__viruses are smallest non cellular infectious particles consisting only on viral DNA enclosed in protein coat and can reproduce only in living organisms.

General features:___ (1):the viruses have very small size they can be seen only by electron microscope (2):the size of viruses is from 20 _ 250nm. (3):they are 10__1000 times smaller than bacteria. (4):they can pass through filter from which bacteria can not pass. (5):viruses cannot grow through artificial media. (6):they can reproduce only in living organisms. (7):the viruses are obligate intracellular parasites. (8):the viruses lacks metabolic machinery they use host metabolic machinery. (9):they cause disease in host cell during reproduction.

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