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Bacterial GeneticsBacterial Genetics

Filename BactGene.ppt

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Background ConceptsBackground Concepts

Structure & Function of DNA & RNA

Genetic code Transcription & translation Protein synthesis Gene Regulation: operators,

promotors , repressors

Filename: DNA.ppt

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Lecture OutlineLecture Outline

Genetic Flow Genetic change

Transformation Conjugation Transduction

Plasmids Transposons

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Genetic FlowGenetic Flow

Between Generations of Cells Within Cells

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Genetic Flow Between Genetic Flow Between GenerationsGenerations

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Genetic flow within a Genetic flow within a GenerationGeneration

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The Genetic CodeThe Genetic Code

Genetic information is stored in DNA sequences found in

Chromosomes copy/cell DS- DNA Circular

Plasmids

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PlasmidPlasmid

Smaller than chromosomal DNA

Contains only a few genes

independent of chromosome

circular multiple copies!!

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Griffith’s Transformation Griffith’s Transformation Exp.Exp.

Background Pathogenic bacteria have capsule Nonpathogenic bacteria have no capsule

Experiment: inject live pathogens live nonpathogens dead pathogens live pathogens+dead nonpathogens

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Bacterial TransformationBacterial Transformation

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Live PathogensLive Pathogens

Mouse Dies

recover pathogens

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Live non PathogensLive non Pathogens

Mouse lives

Non pathogens recovered

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Dead PathogensDead Pathogens

Mouse lives

No Pathogens

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Live NonPathogens+Live NonPathogens+Dead PathogensDead Pathogens

Live Pathogens!!

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Genetic Basis of Genetic Basis of transformationtransformation

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Recipient cell takes up Recipient cell takes up DNADNA

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Recombination OccursRecombination Occurs

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Bacterial ConjugationBacterial Conjugation

Sex and the single cell

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Bacterial ConjugationBacterial Conjugationin E. coliin E. coli

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Conjugation between F- Conjugation between F- & F+& F+

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Replication & Transfer Replication & Transfer of F Factorof F Factor

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F- cell converted to F+F- cell converted to F+

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F factor & ChromosomeF factor & Chromosome

Recombination

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F factor produces an HfrF factor produces an Hfr

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Conjugation Between Hfr Conjugation Between Hfr & F-& F-

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Replication & TransferReplication & Transfer

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Recombination in F- CellRecombination in F- Cell

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Viral TransductionViral Transduction

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Phage Infects Donor CellPhage Infects Donor Cell

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Bacterial Chromosome Bacterial Chromosome Broken DownBroken Down

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Bacterial DNA Trapped Bacterial DNA Trapped in Phage Coatin Phage Coat

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Bacterial DNA Infects Bacterial DNA Infects New CellNew Cell

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Recombination can Recombination can OccurOccur

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TransposonsTransposons

“Jumping Genes” First discovered in corn Genetic element Moves other genes from place to

place on the chromosome Moved genes may be regulated

differently

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Insertion Sequence Insertion Sequence “IS1”“IS1”

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Complex TransposonComplex Transposon

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R Plasmid “R1”R Plasmid “R1”