Virus
- Study of virus is called virology.
- Virus was discovered by Russian scientist Ivanovsky in the year 1892 ( During the test of Mosaic disease in the tobacco)
- In the nature, there are ultra microscopic particle know as viruses.
- It has both the characters of living and non living, so it is a connecting link between living & non living.
- Dr. Stanley first isolated the virus causing mosaic disease in tobacco in the from of crystals.
Characters of virus
- They became active inside a living cells.
- Nucleic acid replicate themselves and they reproduce rapidly.
- They cause disease like bacteria & fungi. According to parasitic nature, virus is of three types----
- Plant virus-RNA is present as its nucleic acid.
- Animal virus-DNA or something RNA is found in it.
- Bacteriophage-They depend only on bacteria. They kill the bacteria. DNA is found in them. Example-T-2 phage
- In man virus cause disease like mumps, chicken pox, hepatits, polio, AIDs and Herpes.
- HIV often change its shape due to the presence of an enzyme reverse transcriptase.
- The enzyme integrase produced by virus allow the integration of HIV-DNA into the host cell DNA.
- EBOLA is virus, causes ebola fever. Fruit Bats are the natural host of this virus, first outbreak in West Africa.
- Bacteriophages:Bacteriophages are those virus which infect the bacteria, Example-Tobacco mosaic virus.
Note:Those viruses in which RNA is found as genetic material are called Retrovirus.
(written by the book Lucent's)
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