The available records shows that the viruses attack bacteria ,cyanobacteria[Blue-green
algae],flowering plants and animals,Depending on the kind of the living organism attacked by them ,the viruses belong to the following four types; 1.Bacterial viruses.usually called bacteriophages,these viruses attack bacteria .If a small amount of bacteriophage suspension is added to a liquid medium with rich bacterial growth , then the turbid liquid medium becomes clean and full of bacteriaophages. 2.Blue-green algae viruses.These viruses usually called cyanophages,attack blue-green algae ,now called cyanobacteria. 3.Plant viruses .These viruses attacks flowering plants ,e.g.,tobacco-mosaic virus,tomato-wilt virus ,yellow and vein mosaic virus,etc. 4.Animal viruses .These viruses attack animals and include influenza virus, rabies virus,pox virus,mumps virus ,polio virus ,measle virus ,vacinnia virus ,adeno virus ,etc. DNA and RNA Viruses .Depending on the presence of DNA or RNA,the viruses are either DNA virus or RNA virus .The DNA virus contains DNA in its core ,whereas the RNA virus has RNA in its core .The bacteriophages are DNA virus and plant viruses are either DNA or RNA virus . Reverse transaction viruses .These are animal viruses ,strongly linked to cancer or tumor formation ,and have RNA in thier core .Usually the DNA makes copy of sequence of its nitrogenous bases in the RNA [transcription], but in these viruses ,the RNA makes copy of sequence of its nitrogenous bases on the DNA [reverse transcription] hence these are called reverse transcription viruses or retroviruses in the abbreviated form .The hepatitis B virus , Epstein-barr virus ,herpes virus and papilloma virus are examples of retroviruses.
algae],flowering plants and animals,Depending on the kind of the living organism attacked by them ,the viruses belong to the following four types; 1.Bacterial viruses.usually called bacteriophages,these viruses attack bacteria .If a small amount of bacteriophage suspension is added to a liquid medium with rich bacterial growth , then the turbid liquid medium becomes clean and full of bacteriaophages. 2.Blue-green algae viruses.These viruses usually called cyanophages,attack blue-green algae ,now called cyanobacteria. 3.Plant viruses .These viruses attacks flowering plants ,e.g.,tobacco-mosaic virus,tomato-wilt virus ,yellow and vein mosaic virus,etc. 4.Animal viruses .These viruses attack animals and include influenza virus, rabies virus,pox virus,mumps virus ,polio virus ,measle virus ,vacinnia virus ,adeno virus ,etc. DNA and RNA Viruses .Depending on the presence of DNA or RNA,the viruses are either DNA virus or RNA virus .The DNA virus contains DNA in its core ,whereas the RNA virus has RNA in its core .The bacteriophages are DNA virus and plant viruses are either DNA or RNA virus . Reverse transaction viruses .These are animal viruses ,strongly linked to cancer or tumor formation ,and have RNA in thier core .Usually the DNA makes copy of sequence of its nitrogenous bases in the RNA [transcription], but in these viruses ,the RNA makes copy of sequence of its nitrogenous bases on the DNA [reverse transcription] hence these are called reverse transcription viruses or retroviruses in the abbreviated form .The hepatitis B virus , Epstein-barr virus ,herpes virus and papilloma virus are examples of retroviruses.
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