Ch 8 How DNA changes cont'

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Ch 8 How DNA changes (cont.)

• Recombination

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Recombination

• To get different combinations of genes
• Donor cell donates a copy of all or part of its
  genes to a recipient cell
• The recipient cell takes up the donor DNA and
  incorporates it into its genetic message
  (recombinant DNA)
• normally only occurs within a species

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Methods of recombination - transformation pg. 231
Griffith 1928 Streptococcus pneumoniae
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Methods of recombination - transformation pg. 231
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Methods of recombination - transformation pg. 231
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Methods of recombination - transformation pg. 231
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Methods of recombination - transformation pg. 231
Genetic material coding for a capsule was
transferred from the dead bacteria to the live
ones.
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Methods of recombination - transformation pg. 231
Genetic material coding for a capsule was
transferred from the dead bacteria to the live
ones. 1944 - Avery, MacLeod, McCarty showed that
it was DNA
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Methods of recombination - transformation pg.
232another example
Naked DNA
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Methods of recombination - transformation pg. 232
Recipient cell must be competent - late log phase
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Methods of recombination - transformation
pg. 232
Uptake of naked DNA Usually transfers 1 or 2 genes
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Methods of recombination - transduction
pg. 234

• Virus transfers DNA into host cell

Bacterial virus
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Methods of recombination - transduction pg. 234
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Methods of recombination - transduction pg. 234
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Methods of recombination - transduction pg. 234
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Methods of recombination - transduction pg. 234
Usually transfers one or two genes
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Methods of recombination - low frequency
conjugation pg 233
Male cell
Female cell
ABC
A-B-C-
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Methods of recombination - low frequency
conjugation pg 233
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Methods of recombination - low frequency
conjugation pg 233
Transfer of F factor only - no chromosomal genes
ABC
A-B-C-
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F becomes an Hfr (high frequency transfer )
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F becomes an Hfr
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F becomes an Hfr
High frequency transfer cell
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Conjugation - high frequency transfer
A-B-C-
ABC
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Conjugation - high frequency transfer
A
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Conjugation - high frequency transfer
Transfer of chromosomal genes, but not usually
the F factor
ABC
AB-C-
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Types of plasmids

• F factor - E. coli

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Types of plasmids

• F factor - E. coli
• ex. Of a transposon (can be integrated into the
  bacterial DNA)

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Types of plasmids

• 2. Dissimilation
• catabolism of unusual compounds
• ex. Pseudomonas - oil

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Types of plasmids

• 3. Bacteriocinogenic
• bacteriocins (proteins which kill other
  bacteria)
• ex. Pseudomonas

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Types of plasmids

• 4. Toxigenic
• toxins
• ex. Staphylococcus aureus - food poisoning

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Types of plasmids

• 5. Resistance (R) factors
• resistance to antibiotics
• can have genes for resistance to many different
  antibiotics
• ex. Shigella
• can be transferred by conjugation and transduction

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R plasmids
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Transposons

• moveable DNAs