Virus (unique organism)

Virus (unique organism)

Viruses are the submicroscopic nucleoproteins entitle which reproduce inside the living host. According to Bawden (1943), the virus is an obligatory parasite pathogens having diameter of less than 200 millimicrons.

 Virus are the smallest living organism (20 nm to 300 nm), made up of 2 components nucleoid and capsid. Nucleoid is made up of nucleic acids forms the inner core of viruses. The nucleic acid is infective agent and contains genetic information. The nucleic acid is either DNA or RNA. The nucleic acid occupies 1 to 4% of the whole amount of virus. Plant viruses possess RNA only while the bacteriophages contain DNA only; about half of animal viruses contain half DNA and half RNA. Capsid forms a covering around the nucleoid. It is inert nongenetic and protective in function. It is made up of protein subunits called capsomers. The capsomers are closely packed and arranged in the helical or polyhedral geometric forms. The complete mature virus is referred to as a viron.

Virus - Diagram
Virus – Diagram
Source

Characteristics of viruses

  1. Virsues are obligate intracellular parasites and are able to carry out typical life functions until they are inside the host cell.
  2. Viruses are nucleoproteins of high molecular weight and have the power of multiplication.
  3. They cause many highly infectious diseases of animals including man, angiosperms, bacteria and fungi.

Living characteristics of viruses

  1. They can grow and reproduce with in the host cell.
  2. They undergo mutations like living organisms.
  3. They possess the genetic materials DNA and RNA.
  4. They respond to light, chemical, temperature etc.

Non-living characteristics of viruses

  1. They lack true cellular structures.
  2. They do not respire.
  3. They are incapable of performing life function without proper host.
  4. Some viruses can be crystallized like a chemical substance e.g. tobacco mosaic virus.
Read this one too :   Darwinism - NEB Biology Notes XI

Economic importance of Viruses

  1. Bacteriophages are used in treatment of dysentery, cholera, plague and many other bacterial diseases.
  2. The temperature phages virus helps in transduction of genetic material from one bacterium to the other.
  3. Virus cause numerous diseases in human being as like polio, rabies, chicken pox, AIDS, anthrax etc.
  4. Some of the common viral plant diseases are tobacco mosaic, leaf roll of potato etc.

Types of Viruses

On the basis of host

1. Animal virus 

2.Plant virus 

3. Bacteriophage

Bacteriophage Virus

On the basis of nucleic acids

1. DNA virus 

2.RNA virus 

3.DNA-RNA virus

On the basis of number of strands

1. Double stranded DNA 

2.Single stranded DNA 

3.Double stranded RNA 

4.Single stranded RNA

ednepednep

About Post Author

ednep

administrator
Happy
Happy
%
Sad
Sad
%
Excited
Excited
%
Sleepy
Sleepy
%
Angry
Angry
%
Surprise
Surprise
%

Average Rating

5 Star
0%
4 Star
0%
3 Star
0%
2 Star
0%
1 Star
0%

Leave a Reply

ednep
ednep

Ednep.com is a platform that aims to provide educational materials in the form of courses, articles, tutorials, syllabus, opportunities and more.