o Bacteriophages are viruses that parasitize bacteria.
o Bacteriophages were jointly discovered by Frederick Twort (1915) in England and by Felix d'Herelle (1917) at the Pasteur Institute in France. Felix d'Herelle coined the term “Bacteriophage”.
o Bacteriophage means to eat bacteria, and are called so because virulent bacteriophage can cause the compete lysis of a susceptible bacterial culture.
o They are commonly referred as “phage”.
o Phages are obligate intracellular parasites that multiply inside bacteria by making use of some or all of the host biosynthetic machinery.
o They occur widely in nature and can readily be isolated from feces and sewage. There are at least 12 distinct groups of bacteriophages, which are very diverse structurally and genetically.
Examples of phages:
ü T-even phages such as T2, T4 and T6 that infect E.coli
ü Temperate phages such as lambda and mu
ü Spherical phages with single stranded DNA such as PhiX174
ü Filamentous phages with single stranded DNA such as M13
ü RNA phages such as Qbeta
Depending upon the phage, the nucleic acid can be either DNA or RNA but not both. The nucleic acids of phages often contain unusual or modified bases, which protect phage nucleic acid from nucleases that break down host nucleic acids during phage infection. Simple phages may have only 3-5 genes while complex phages may have over 100 genes. Certain phages are known have single stranded DNA as their nucleic acid.
محتويات مواقع أعضاء هيئة التدريس بما فيها من نصوص وملفات وصور وأبحاث وأية مواد أخرى هي مسئولية عضو هيئة التدريس بالكامل بصفته صاحب الموقع وبما له من صلاحية مطلقة في الإضافة والحذف، وتخلي الجامعة مسئوليتها عن محتويات تلك المواقع.
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