Bacteriophage Genetics

T2 and its close relative T4 are viruses that infect the bacterium E. coli. The infection ends with destruction (lysis) of the bacterial cell so these viruses are examples of bacteriophages ("bacteria eaters").

Each virus particle (virion) consists of:

  • a protein head (~0.1 ┬Ám) inside of which is a single, circular molecule of double-stranded DNA containing 166,000 base pairs.
  • a protein tail from which extend
  • thin protein fibers

Life Cycle:

  • The virus

Index to this page

Mapping Within A Gene: the RII Locus

T2 and its close relative T4 are viruses that infect the bacterium E. coli. The infection ends with destruction (lysis) of the bacterial cell so these viruses are examples of bacteriophages ("bacteria eaters").

They have been enormously useful in genetic studies because:

  • Viruses of two (or more)

Chromosomes

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Composition

In eukaryotes, chromosomes consist of a single molecule of DNA [Link to visual proof] associated with:

  • many copies of 5 kinds of histones. Histones are proteins rich in lysine and arginine residues and thus positively-charged. For this reason they bind tightly to the negatively-charged phosphates in DNA.
  • a small number of copies of many