Kamis, 30 Juli 2015

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Composed of Nucleic Acid and Protein Envelope Virus


A Virus is not a cell (acellular). A virus contains a particle called virion, which can be crystallized and shows a mineral characteristics rather than life. For that matter, some scientists consider viruses as non-living. Still, other think the opposite because viruses can reproduce which is a characteristic of life. Nevertheless, viral reproduction can only be done inside a living cell. The cell in which the virus resides is called the host cell.

Because a virus is not a cell, it does not have cellular component such as the cell membrane, cytoplasm, and nucleus. A virus is composed of a nucleic acid and protein coat called a capsid.

Nucleic Acid

Nucleic Acid Are the molecules that carry the genetic information. A virus has only one type of the nucleic acids, i.e. DNA or RNA

The genetic material may be in the shape of single of double stranded chain, circular, or linier.

Protein Envelope (capsid)

The protein coat covering the genetic material is called the capsid

Composed of a large number protein subunits called capsomers. The capsid giving the virus its shape. It can be a helical structure of capsomeres, giving the virus its rod shape, or polyhedral, or a more complex shape

The T shape virus has a head and tail part and the head is usually polyhedral and the tail is composed of three structures called sheath, base plate, and tail fibers. The base plate and tail fiber are used to attach and infect cell. An example of one of these complex viruses is the T shape bacteriophage.

Body and structure of a virus. Virus is composed of nucleid acid and capsid

a. helical such as tobacco mossaic virus
b. polyhedral such as adenovirus
c.complex such as Bacteriophage
d.virus with envelope in influenza

Nucleic acid and capsid from a structure called nucleocapsid. In some viruses, the nucleocapsid. In some viruses, the nucleocapsid has a membrane called envelope. it is composed of lipids and protein and helps the virus to infect cells. An example of a virus with an envelope is the Influenzavirus. Viruses without an envelope are called naked virusses

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