Viruse by vijay sir

 

           Viruses are unicellular, ultramicroscopic organisms. They reproduce inside living cells, pass through filters and are covered coat.

General Properties of Viruses

·         They do not possess cellular organization.

·         They contain either RNA or DNA.

·         They lack enzymes necessary for protein and nucleic acid        synthesis.

·         They depend on synthetic machinery of host cells.

·         They multiply by complex processes .

·         They are unaffected by antibiotics.

·         They are sensitive to interferon.

Morphology of Viruses

Size

Viruses vary widely in size –

1.      Largest virus measuring 300 nm.

  2.    Smallest virus measuring 20 nm.

Shape

Viruses have characteristics shape –

1.      Rabies virus has bullet shape.

2.      Pox virus has brick shape.

3.      Polio virus has round shape.

Structure

Viruse has the following parts :

1.      Central core of nucleic acid ( RNA OR DNA)

2.      Protein coat around central core called capsid.

3.      Subunits of capsid known as capsomere.

4.      Envelope

Classification of viruses

Viruses are classified into three groups depending on the type of nucleic acid they posses.

Major groups of DNA viruses

1.    Pox Viruse 
2.    Herpes Viruse 
3.        Adeno  viruse 
4.    Papova viruse

Major groups of RNA viruses

1.      Picorna Viruse 
2.     Rhabdo Viruse 
3.     Para myxo Viruse  
4.     Retro Viruse 
5.     Toga Viruse