Virus means venom or the poison or the poisonous fluid. It was given by Louis Pasteur.
It is a connecting link between living and non-living
Virus are intercellular, an obligate parasite, a self-replicating non-cellular obligate parasite, self-replicating non-cellular, sub-microscopic organisms
They lack cellular organelles like ribosomes, mitochondria.
Living Characters Of Virus
- A virus has living material.
- Have definite shape and size.
- Genetic material DNA or RNA.
- They can grow.
- It can be transmitted from one host to another.
- They can do multiplication within the host.
- Shows irritability.
- It can bring enzymatic chanINFLUENZAges in vitro.
- They are able to infect and cause disease to live organisms.
- They can mutate.
- DNA and proteins of the virus are similar to those of higher organisms.
Non-Living Characters of Virus
- They are inactive outside the body of the host.
- They have either DNA or RNA.
- There is no cell wall membrane or cytoplasm.
- There is no metabolism.
- They are not able to do any fiction unless they obtain metabolic products from others.
- Energy producing enzyme system is absent.
Some Unique Characters of Virus
- Presence of only DNA or RNA.
- Do not show cell division.
- They use the metabolic machinery of the host cell to replicate.
- Examples of Virus, HIV, Hepatitis B, Ebola, Adenovirus, Bacteriophage
Structure of Virus
- The virus is a parasitic cell replicating, non-cellular, sub-microscopic organisms.
- A simple particle of a virus is known as Virions.
- It has a protein covering called Capsid.
- It is made up of capsomeres.
- These sub-units are arranged in helical or polyhedral forms.
- It has one type of nucleic acid either DNA or RNA.
- If the virus has DNA it is known as deoxyvirus and if the virus has DNA. It is known as the ribovirus.
Classification of Virus
It is of two types:-
Plant Virus- plant virus
Animal Virus- zoo virus
But some other categories are also found in the virus which is as follows:-
Synophage– Blue-green algae
Mycovirus– a virus which affects fungi
Phycovirus– affects algae
Single Strand of DNA
Ex: Coliphage Virus
Double Strand of DNA
Ex: Herpes Virus
Single Strand RNA
Double Strand of RNA