Viruses in Bacteria

Bacteriophage is a type of virus that infects a bacteria.

Bacterial Viruses - 1

-Viruses that infect bacteria
-Intended as control tool for bacteria but phages cleared rapidly

Bacterial Viruses - 2

• COMPOSITION OF BACTERIOPHAGE
– DNA or RNA

– often contain unusual or modified bases

– Modified bases protect from host nucleases

• The size of the nucleic acid varies depending upon the phage.
– Simplest phages code for 3-5 average size gene products

– Complex phages may code for over 100 gene products


Bacterial Viruses - 3

• STRUCTURE OF BACTERIOPHAGE
• Bacteriophage come in many different sizes and shapes

– 1. Size - T4 is among the largest phages; it is approximately 200 nm long and 80-100 nm wide. Other phages are smaller. Most phages range in size from 24-200 nm in length

– 2. Head or Capsid - All phages contain a head structure which can vary in size and shape. Some are icosahedral (20 sides) others are filamentous. The head or capsid is composed of many copies of one or more different proteins. Inside the head is found the nucleic acid. The head acts as the protective covering for the
nucleic acid.

– 3. Tail - Many but not all phages have tails attached to the phage head