Virus

• Virus was discovered by => Dimitri Ivanovsky (In 1892).
• Dimitri Ivanovsky discover virus during investigation of plant disease called Tobacco mosaic.
• Study of Virus is called as Virology.
• First discovered virus => Tobacco mosaic virus.

Characteristics of Virus:

1. Complete lack of cellular level composition like Cytoplasm, Cell membrane, Cell organelles etc.
2. Inside plant viruses transmit through phloem and Inside animal viruses transmit through blood.
3. Viruses have either DNA or RNA but both never.
4. viruses is composed of neucleoproteins.
5. Viruses is assumed as accessories of living and non-living organisms. Thus viruses exhibit the properties of both living & non-living.

Sr. No.	Living properties of Virus	Non-Living properties of Virus
1	The presence of DNA or RNA.	Absence of cell.
2	Structural diversity.	Lack of protoplasm.
3	Geneticity & Parasitic properties.	Non re-productivity & growth outside
4	Sensitivity and Evolution.	Stored in the form of crystal outside
5	To spread diseases.	Lack of metabolic activities like

Structure of Virus:

 

      There are three main constituents(Components) in the structure of virus.

1. Protein caspid.
2. Nucleic acid (DNA or RNA).
3. Thick outer layer.

• In plant virus nucleic acid RNA is present.
• In animal virus nucleic acid DNA is present.

Types of Virus:

1) Plant Virus:

• This is a nucleic acid of RNA.
• The virus yellow mosaic virus (YMV) is a plant virus.

2) Animal Virus:

• This is a nucleic acid of DNA or RNA & usually spherical in shape.
• The virus like influenza, mups etc. are animal virus.

3) Bacteriophase:

• Such virus only depend on bacteria.
• In this virus DNA are present only & can destroy other viruses.
• It is also called as T2 Phase virus.

Advantages of Viruses:

• Used in study of Biotechnology.
• Bacteriophase virus used as a water preservative & due to its presence water doesn't rotten & remains fresh. 
• Viruses are useful in cleaning the blue green algae. 

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