Virus

INTRODUCTION- Virus is also called as obligate parasite, because it depends upon the some parasite (host) cell of organisms and having ability to kill that host. Viruses are non cellular and living. Virus is composed of Nucleic acid. After entering into the host cell,it form protein envelope around the nucleic acid. The size of virus is so tiny and range between 20-300 nm. 1 bacteria can hold around 1000 of virus. virus cannot grow on artificial media because they have no mechanism to produce their own protein, hence they are totally depend upon host cell and utilizes the protein produce by host cell. Host cell stand for cell it can be bacteria, animal, human,plant,etc. The genetic information of viruses are either DNA or RNA and not both at a time in a virus. If it is a DNA either single stranded or double stranded but not both at a time.


CLASSIFICATION:- 1)Dermatotropic
                                    2)Neurotropic
                                    3) Viscerotropic

                                    4)Rneumotropic

STRUCTURE:- 1) nucleic acid
                          2) capsid and envelope
                          3) enveloped virus
                          4) complex virus