What are the three mechanisms for genetic transfer?
Transformation, Conjugation and Transduction
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What is Transformation?
The transfer of genetic material as free DNA to recipient cells, with no direct contribution from the intact donor bacterium.
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What is Conjugation?
A mechanism of gene transfer that depends on the presence of a conjugative plasmid in the donor organism and involves cell-tocell contact between donor and recipient bacteria.
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What is Transduction?
The transfer of donor bacterial genetic material to recipient cells by a defective bacteriophage particle.
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What is a Plasmid?
Autonomous, independently replicating genetic elements that usually confer additional phenotypes on the bacteria that harbour them.
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How do bacteria protect their own DNA from their restriction enzymes?
They modify it usually by methylation within the recognition sequence.
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What sites to restriction enzymes recognise?
Specific symmetrical sequences in DNA, usually palindromes, that are 4 to 6 base pairs long.
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Bacteria show clonal growth, what does that mean?
All cells in a bacterial colony are genetically identical. The same is true of a plaque.
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What are the advantages of studying genes in bacteria instead of eukaryotes?
It is simple, cheap and quick.
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What is a clone?
A groupof individuals derived by a vegetative (non-sexual) process from a single individual.
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How does conjugal DNA transfer occur?
By rolling circle replication. The gene traZ encodes an endonuclease which makes a nick in the plasmid DNA at a site called oriT (origin of transfer).
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What can you deduce if two genes are consistently co-transformed?
That they are so close together on the chromosome that they are highly likely to remain together during random fragmentation of DNA. (co-transformation indicates close genetic linkage)
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What are the main types of bacterial mutants?
Nutirtional mutants, Resistance mutants and Conditional lethal mutants.
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What is a merodiploid?
A bacterium that contains its own entire chromosome plus a part of the chromosome of a donor cell.
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Other cards in this set
Card 2
Front
What is Transformation?
Back
The transfer of genetic material as free DNA to recipient cells, with no direct contribution from the intact donor bacterium.
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