Virus

A virus was discovered by Adolf Meyer in 1883. A virus is a metaorganism or transitional organism (organisme peralihan), because the characteristic is like living thing (only can develop in the living organism) and inanimate (because virus can be critalized, while the other living thing can’t be cristalized).

Virus is acellular organism (not a cel organism). Why? Because virus doesn’t have a cel membrane, protoplasm, and so on. It only has nucleolus in the form of DNA or RNA and selubung protein.

The structure of viruses  can be seen in Bacteriophage virus or bacteria eater virus:

1.Head > there is DNA or RNA. DNA found on the T4 virus, while RNA found on the AIDS, polio and influenza virus. The shape of the virus’ head is like octagonal (segi 8).

2.Tail Fiber > this fiber will stuck in the  cell when attacked. The virus’ tail is covered with capsid (protein coat) containing protein.

3.Skin > arranged from protein.

The shapes of virus : various shapes of virus, namely cylindrical, oval, square, elongated (memanjang), polihedral.

The size of virus : Viruses are usually much smaller than bacteria and are submicroscopic.  Most range in size from 5 to 300 nanometers (nm), although some Paramyxoviruses can be up to 14,000 nm long.

1.Lytic Cycle > virus yg melangsungkan daur litik disebut VIRULENT. Daur litik terdiri dari 3 tahap Adsorption and Penetration Stage, replication stage, lyses stage.

2.Lysogenic Cycle > virus yg melangsungkan daur lisogenik disebut TEMPERATE  VIRUS. Daur lisogenik terdiri atas 3 tahap juga: Adsorption and Penetration Stage, gene insertion stage, division stage.

-Berdasarkan jenis sel inang yang diinfeksi: virus manusia, hewan, tumbuhan, bakteri.

  Virus manusia > menginfeksi manusia, dst

-Berdasarkan jenis materi genetika: virus DNA > contoh adenovirus, virus herpes dan virus RNA > contoh    virus rabies, influenza, polio. 

Note:

Virus hanya dapat bereproduksi apabila berada dalam sel makhluk hidup karena virus hanya dapat bereproduksi di dalam material hidup dengan menginvasi dan mengendalikan sel makhluk hidup karena virus tidak memiliki perlengkapan selular untuk bereproduksi sendiri
# bberapa soal ttg virus n jawaban  http://id.answers.yahoo.com/question/index?qid=20100814055933AAFMybS