Transcript Foundations of Biology

Colossians 1:16, 17
16 For 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:
17 And he is before all things, and by
him all things consist.
©2000 Timothy G. Standish
Bacterial Genetics
Timothy G. Standish, Ph. D.
©2000 Timothy G. Standish
Bacteria Have Circular
Chromosomes
Cell Wall
Cell Membrane
Chromosome
Origin of
Replication
Cytoplasm
Termination of
Replication
©2000 Timothy G. Standish
Replication
Replication goes
in both directions
Original
Chromosome
Start of replication
Theta (q) structure
Mid replication
End of replication
Two chromosomes
©2000 Timothy G. Standish
Binary Fission Revisited
©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

©2000 Timothy G. Standish
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
©2000 Timothy G. Standish
Transformation
Crossing
over
Insertion
©2000 Timothy G. Standish
Transduction
Generalized
Infection
Destruction of
the bacteria’s
DNA
Production of
viral parts
Lysis
Packaging
Replication of
the viral
genome
©2000 Timothy G. Standish
Temperate
Phage
Transduction
Specialized
Part of the
bacteria’s
DNA
Production of
viral parts
Lysis
Packaging
Replication of
the viral
genome
©2000 Timothy G. Standish
F plasmid
Conjugation
F+ bacteria
Mating Bridge
F- bacteria
©2000 Timothy G. Standish
F plasmid
Conjugation
F+ bacteria
Mating Bridge
Original
F+ bacteria
F- bacteria
New
F+ bacteria
©2000 Timothy G. Standish
Hfr Recombination
F+ bacteria
F plasmid
Integration
Hfr cell
F- bacteria
Transfer of
genetic material
©2000 Timothy G. Standish
Hfr Recombination
F+ bacteria
F plasmid
Integration
Hfr cell
Interruption
of conjugation
F- bacteria
Crossing over
Transfer of
genetic material
©2000 Timothy G. Standish
Hfr Recombination
F+ bacteria
F plasmid
Integration
Hfr cell
F- bacteria
Recombinant
Bacteria
©2000 Timothy G. Standish
Transcription And Translation
In Prokaryotes
5’
3’
3’
5’
RNA
Pol.
Ribosome
mRNA
Ribosome
5’
©2000 Timothy G. Standish
©2000 Timothy G. Standish