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©2000 Timothy G. Standish Colossians 1:16, 17 16For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether they be thrones, or dominions, or principalities, or powers: all things were created by him, and for him: 17And he is before all things, and by him all things consist.
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©2000 Timothy G. Standish Bacterial Genetics Timothy G. Standish, Ph. D.
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©2000 Timothy G. Standish Cell Wall Cytoplasm Cell Membrane Bacteria Have Circular Chromosomes Termination of Replication Origin of Replication Chromosome
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©2000 Timothy G. Standish Replication End of replication Two chromosomes Original Chromosome Start of replication Theta ( ) structure Replication goes in both directions Mid replication
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©2000 Timothy G. Standish Binary Fission
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©2000 Timothy G. Standish 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
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©2000 Timothy G. Standish Ways Bacteria Exchange Genetic Material 1 Transformation - Bacteria take up DNA from their environment and incorporate it into their genome (i.e. the Griffith experiment) 2 Conjugation - The direct transfer of DNA by bacteria usually via plasmids 3 Transduction - Movement of DNA between bacteria by viruses
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©2000 Timothy G. Standish 1 Transformation Insertion Crossing over
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©2000 Timothy G. Standish 1 Transformation
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©2000 Timothy G. Standish 1 Transformation
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©2000 Timothy G. Standish 1 Transformation
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©2000 Timothy G. Standish 1 Transformation
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©2000 Timothy G. Standish 1 Transformation
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©2000 Timothy G. Standish Crossover Frequency Following binary fission, one daughter cell will have the recombinant strand and thus have a recombinant chromosome Mapping bacterial genes following transformation is not significantly different from eykaryotic mapping. The closer two genes are to one another, the lower the probability of a crossover event between them and thus the higher the probability that they will be co-transformed A B C A BC Transformation with A and C is unlikely
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©2000 Timothy G. Standish F - bacteria 2 Conjugation F plasmid Mating Bridge F + bacteria F plasmid
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©2000 Timothy G. Standish 2 Conjugation F - bacteria F plasmid F + bacteria F plasmid Mating Bridge
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©2000 Timothy G. Standish 2 Conjugation F - bacteria F plasmid F + bacteria F plasmid Mating Bridge
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©2000 Timothy G. Standish 2 Conjugation F - bacteria F plasmid F + bacteria F plasmid Mating Bridge
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©2000 Timothy G. Standish 2 Conjugation F - bacteria F plasmid F + bacteria F plasmid F plasmid Mating Bridge
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©2000 Timothy G. Standish Transfer of genetic material Hfr Recombination F + bacteriaF - bacteria F plasmid Integration Hfr cell
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©2000 Timothy G. Standish Hfr Recombination F + bacteriaF - bacteria Crossing over Transfer of genetic material Interruption of conjugation Hfr cellF plasmid Integration
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©2000 Timothy G. Standish Hfr Recombination F + bacteria Hfr cellF plasmid Integration F - bacteria Recombinant Bacteria
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©2000 Timothy G. Standish 3 Transduction Generalized Destruction of the bacteria’s DNA Lysis Replication of the viral genome Production of viral parts Packaging Infection
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©2000 Timothy G. Standish 3 Transduction Specialized Temperate Phage Part of the bacteria’s DNA Replication of the viral genome Production of viral parts Packaging Lysis
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©2000 Timothy G. Standish
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