Microbial Reproduction

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Microbial Reproduction

• SC.912.L.16.7

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Gene transfer between organisms

• 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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How do bacteria transfer genetic material to each
other?

• Remember, prokaryotes have no nucleus.
• Bacteria somatic genome, circle of
  double-stranded DNA
• Optional smaller circles of DNA plasmids.
• 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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Bacteria Cell
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Genetic Recombination

• Nonreproductive Methods bacteria can acquire
  new genetic material.

Characteristic Transformation Conjugation Transduction
Method of DNA Transfer Across cell wall and cell membrane of recepient Through a conjugation bridge between two cells By a virus
Plasmid transfer Yes Yes Not likely
Chromosome transfer No Sometimes No
Antibiotic resistance acquired Yes Yes Sometimes
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Transformation
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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Conjugation

• A type of Bacteria Sex
• Two organism swap genetic information, that
  contains the information such as a resistance to
  penicillin

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Conjugation
A hollow bridge forms, the pilus, between two
bacterial cells, and genes move from one cell to
the other
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Transduction
Transduction is the process by which DNA is
transferred from one bacterium to another by a
virus
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Viral Replication

• 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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Lytic Cycle
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Lysogenic Cycle

• Nucleic acid of virus becomes part of the host
  cells 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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Lysogenic Cycle
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Lytic vs Lysogenic
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Genetic engineering techniques how to insert new
genes

• 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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Biotechnology and human uses

• 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