Transcript Lecture Chpt. 18 Bacteria

The Genetics of
Bacteria
Bacterial Genome:
o Circular DNA - double stranded
`
aka. its chromosome in nucleoid
o Plasmid - small circles of
“extra” DNA - not necessary
for survival, however important traits
fertility factor, antibiotic resistance
Bacterial chromo. replicates
Bacterial chromo. replicates
-two copies move apart
-cell grows
-plasma membrane pinches
-new cell wall deposited
division
produce
s
Origin of
Replication
Replication in
both
directions
Replication
Forks move
bidirectionly
until they
meet
Genetically
identical
daughter cells
(clones)
mutations produce genetic
variation rapidly b/c
generational time is
sooooooo fast
Genetic Recombination:
Mutants no growth cannot
synthesis
required
amino acid
Genetic Recombination:
Combine
growth
Genetic Recombination:
o Transformation - uptake of
`
“naked” DNA from the environment
o Transduction o Conjugation -
Genetic Recombination:
o Transformation - uptake of
`
“naked” DNA from the environment
into its chromosome.
Genetic Recombination:
o Transformation
`
Genetic Recombination:
o Transduction `
A phage (virus) transfers
bacterial genes from one
host cell to another.
Genetic Recombination:
o Transduction `
A phage (virus) transfers
bacterial genes from one
host cell to another.
Genetic Recombination:
o Transduction `
A phage (virus) transfers
bacterial genes from one
host cell to another.
Genetic Recombination:
o Transduction `
A phage (virus) transfers
bacterial genes from one
host cell to another.
Genetic Recombination:
o Conjugation - bacterial cells join
`
and transfer genetic material through
a sex pilli.
F factor = fertility factor
+
F
HFR
Genetic Recombination:
o Conjugation - bacterial cells join
`
and transfer genetic material through
a sex pilli.
R plasmid = resistance
plasmid
“moveable genetic elements”
portions
change
locations
within the
chromosome,
or they may
copy into a
new location.
GENETIC
RESHUFFLIN
G
1983 Nobel
prize winner
Transposons - Example
Bacterial Genetic
Recombinations
1. Transformation
2. Transduction
3. Conjugation
4. Plasmids
5. Transposons
Be able to discuss a few of these
methods.