Virus - Components

Description:

A virus mostly consists of two parts: nucleoid (genome) and capsid. An envelope is present in some viruses. A few enzymes are also known to occur occasionally inside the virus.

Nucleoid

• Represents the viral chromosome.

• Nucleic acid is DNA or RNA but never both.

• DNA containing viruses are called deoxyviruses.

• RNA containing viruses are called riboviruses.

• Each of the viruses has two subtypes. Double stranded and single stranded.

Capsid

• It is the proteinaceous covering around the virus which protects the genetic material from physical and chemical agents.

• Capsid consists of a number of subunits called capsomers or capsomeres.

• In some animal viruses there is a loose membrane covering that occurs in some animal virus and rarely in plant and bacterial viruses.

• The viruses without an envelope is called naked virus.