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Bacterial Genetics. Timothy G. Standish, Ph. D. Cell Wall. Cell Membrane. Cytoplasm. Origin of Replication. Chromosome. Termination of Replication. Bacteria Have Circular Chromosomes. Replication goes in both directions. Original Chromosome. Start of replication
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Bacterial Genetics Timothy G. Standish, Ph. D.
Cell Wall Cell Membrane Cytoplasm Origin of Replication Chromosome Termination of Replication Bacteria Have Circular Chromosomes
Replication goes in both directions Original Chromosome Start of replication Theta (q) structure Mid replication End of replication Two chromosomes Replication
Genetic Recombination • If bacteria were incapable of genetic recombination, all members of a given species would be clones with differences arising only due to mutations in different lines • If bacteria could not share genetic information as other organisms do in sexual reproduction, there would be vastly less opportunity to adapt to different environments • As it turns out, bacteria are notorious for their ability to adapt, thus it is not surprising that elegant mechanisms exist for sharing genetic information
Ways Bacteria Exchange Genetic Material • Transformation - Bacteria take up DNA from their environment and incorporate it into their genome (i.e. the Griffith experiment) • Transduction - Movement of DNA between bacteria by viruses • Conjugation - The direct transfer of DNA by bacteria usually via plasmids
Transformation Crossing over Insertion
Destruction of the bacteria’s DNA Infection Replication of the viral genome Production of viral parts Packaging Lysis TransductionGeneralized
Temperate Phage Part of the bacteria’s DNA Replication of the viral genome Production of viral parts Packaging Lysis TransductionSpecialized
F plasmid F- bacteria Conjugation F+ bacteria Mating Bridge
F plasmid Conjugation F+ bacteria Mating Bridge Original F+ bacteria F- bacteria New F+ bacteria
F plasmid Integration Hfr cell F+ bacteria F- bacteria Transfer of genetic material Hfr Recombination
F plasmid Integration Hfr cell F+ bacteria F- bacteria Crossing over Hfr Recombination Interruption of conjugation Transfer of genetic material
F plasmid Integration Hfr cell F+ bacteria F- bacteria Hfr Recombination Recombinant Bacteria
The End
5’ 3’ 3’ 5’ RNA Pol. Ribosome mRNA Ribosome 5’ Transcription And Translation In Prokaryotes