Microbial genetics micr340
This presentation is the property of its rightful owner.
Sponsored Links
1 / 15

Microbial Genetics (Micr340) PowerPoint PPT Presentation


  • 58 Views
  • Uploaded on
  • Presentation posted in: General

Microbial Genetics (Micr340). Lecture 10 Lytic Bacteriophages (II). Genetic Analysis of Phages. Genetic analysis – study of relationship (and distance) between different mutants using genetic approaches such as recombination and complementation Phage’s advantages: Short generation time

Download Presentation

Microbial Genetics (Micr340)

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Microbial genetics micr340

Microbial Genetics (Micr340)

Lecture 10

Lytic Bacteriophages (II)


Genetic analysis of phages

Genetic Analysis of Phages

  • Genetic analysis – study of relationship (and distance) between different mutants using genetic approaches such as recombination and complementation

  • Phage’s advantages:

    • Short generation time

    • Haploid

    • Phages multiply as clones in plaques

    • Different phages can be crossed


Genetic analysis of phages1

Genetic Analysis of Phages

  • Infection of cells by phages:

    • Permissive host

    • Nonpermissive host

    • Permissive conditions

    • Nonpermissive conditions

  • Multiplicity of Infection (MOI) – the efficiency of infection is affected not only by the concentration of phage and bacteria but also by the ratio of phage to bacteria


Genetic analysis of phages2

Genetic Analysis of Phages

  • Phage crosses – the process in which the mutated DNAs of two members of the same species are put together in the same cell to allow recombination


Genetic analysis of phages3

Genetic Analysis of Phages

  • Recombination tests – the DNA of two parent organisms is assembled in new combinations, so that the progeny have DNA sequences from both parents

  • Recombination frequency: the closer the two regions of sequence difference are to each other, the less room there is for a cross over to occur


Microbial genetics micr340

Recombination


Genetic analysis of phages4

Genetic Analysis of Phages

  • Complementation tests: the gene products synthesized from two different DNAs interact in the same cell to produce a phenotype.


Microbial genetics micr340

Complementation


Genetic analysis of t4 phage

Genetic Analysis of T4 phage

  • Experiments with rII genes

    • r-type of mutations for T4 phage – cause the infected cells to lyse more quickly than the normal (r+) phage

    • rII = “rapidly-lysis mutants type II”


A three factor cross to map r ii genes

A three factor cross to map rII genes


Deletional mapping

Deletional mapping


Generalized transduction

Generalized Transduction

  • Transduction – a process in which bacteriophages carry bacterial DNA from one cell to another during it infect-and-kill cycles

  • Generalized transduction – any region of the bacterial chromosome can be transferred

  • Specialized transduction – only certain genes close to the attachment site of a lysogenic phage in the chromosome can be transferred.


Microbial genetics micr340

GeneralizedTransduction


Microbial genetics micr340

Co-Transduction


  • Login