Transcript L16.7_Microbial Reproduction

SC.912.L.16.7
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In Eukaryotes: gene transfer only from parent
to offspring during sexual reproduction (pre
technology)
In Prokaryotes: genetic transfer common
between individuals, even non-related
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Remember, prokaryotes have no nucleus.
Bacteria: somatic genome, circle of doublestranded DNA
Optional: smaller circles of DNA: plasmids.
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Genes on plasmids allow survival under unusual
conditions.
Bacterium duplicates plasmid, gives a copy to
another cell via a thin tube called a pilus.
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Nonreproductive Methods : bacteria can acquire new
genetic material.
Characteristic
Transformation Conjugation
Transduction
Method of DNA Across cell wall
Transfer
and cell
membrane of
recepient
Through a
By a virus
conjugation
bridge between
two cells
Plasmid
transfer
Yes
Yes
Not likely
Chromosome
transfer
No
Sometimes
No
Antibiotic
resistance
acquired
Yes
Yes
Sometimes
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Transformation is
the process by
which genetic
material is
absorbed from
the outside
environment
This plasmid of DNA is new to the bacteria
added by transformation! Produces the
glowing protein
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A type of Bacteria
Sex
Two organism swap
genetic information,
that contains the
information such as
a resistance to
penicillin
A hollow bridge forms, the pilus, between
two bacterial cells, and genes move from one
cell to the other
Transduction
is the process
by which
DNA is
transferred
from one
bacterium to
another by a
virus
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Can replicate only by invading host cell and using its
enzyme and organelles.
Bacteriophage – viruses that infect bacteria
 Used to study viruses
1. Lytic Cycle
 Viral genome is released into the host cell
 Replication follows immediately
 Cellular components used to make new viruses
 Viral enzyme kills cell.
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Nucleic acid of virus becomes part of the
host cell’s chromosome
Nucleic acid remains in the cell in this form
for many generations
HIV follows this pattern
HIV infects WBC and remains as
proviruses
As immune system fails, opportunistic
infections occur = AIDS
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Electro- and chemical poration: make holes in
cell membrane by chemicals or electric currents
Microinjection: injecting new gene (glass
needle) into the recipient cell
Bioballistics: metals slivers coated with DNA,
ëshotí into cell
Recombinant DNA (uses biological vectors like
plasmids or viruses)
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Use of bacterium plasmids (or viruses):
If bacterium takes up the plasmid with inserted
material, it will make the protein for which the
gene codes.
Example: insulin production