Transcript Foundations of Biology - KSU Faculty Member websites

Bacterial Genetics
Bacteria Have Circular
Chromosomes
Cell Wall
Cell Membrane
Chromosome
Origin of
Replication
Termination of
Replication
Cytoplasm
Replication
Replication goes
in both directions
Original
Chromosome
Start of replication
Theta (q) structure
Mid replication
End of replication
Two chromosomes
Binary Fission Revisited
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
Transduction
Generalized
Infection
Destruction of
the bacteria’s
DNA
Production of
viral parts
Lysis
Packaging
Replication of
the viral
genome
Temperate
Phage
Transduction
Specialized
Part of the
bacteria’s
DNA
Production of
viral parts
Lysis
Packaging
Replication of
the viral
genome
F plasmid
Conjugation
F+ bacteria
Mating Bridge
F- bacteria
F plasmid
Conjugation
F+ bacteria
Mating Bridge
Original
F+ bacteria
F- bacteria
New
F+ bacteria
Hfr Recombination
F+ bacteria
F plasmid
Integration
Hfr cell
F- bacteria
Transfer of
genetic material
Hfr Recombination
F+ bacteria
F plasmid
Integration
Hfr cell
Interruption
of conjugation
F- bacteria
Crossing over
Transfer of
genetic material
Hfr Recombination
F+ bacteria
F plasmid
Integration
Hfr cell
F- bacteria
Recombinant
Bacteria
Transcription And Translation
In Prokaryotes
5’
3’
3’
5’
RNA
Pol.
Ribosome
mRNA
5’
Ribosome