Transduction quiz #1 Flashcards
Transduction quiz #1
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Transduction refers to the conversion of what into what in the context of bacterial genetics?
Transduction refers to the conversion of foreign DNA carried by a bacteriophage into genetic material within a bacterium, resulting in the transfer of DNA between bacteria via a virus. Place the steps of specialized transduction in order.
1. A bacteriophage infects a bacterium and inserts its DNA (transducer) into a specific site in the bacterial chromosome. 2. The phage DNA integrates at this specific sequence. 3. Upon activation (e.g., by a chemical or another virus), the phage DNA excises from the chromosome, sometimes taking nearby bacterial genes with it. 4. The phage packages this hybrid DNA. 5. The phage infects a new bacterium, transferring the specific bacterial genes to the new host. Who discovered the process of transduction in bacteria and in what year?
Transduction was discovered by Lederberg and Zender in 1951. What experimental evidence ruled out conjugation as the mechanism of DNA transfer in the original transduction experiments?
A filter was used that blocked conjugation but still allowed growth, indicating DNA transfer occurred via something smaller, like a bacteriophage. How does generalized transduction differ from specialized transduction in terms of the DNA transferred?
Generalized transduction can transfer any part of the bacterial chromosome, while specialized transduction transfers only specific nearby genes. What role does a transducer play in specialized transduction?
A transducer inserts into a specific sequence in the bacterial chromosome and, upon activation, picks up nearby genes for transfer. Why can cotransduction be used to map gene distances on a bacterial chromosome?
Cotransduction frequency reflects how close two genes are; genes closer together are more likely to be transferred together by a single phage. What happens to bacterial DNA during generalized transduction after a bacterium is lysed?
The bacterial DNA is chopped up and released into the environment, where a bacteriophage can pick up fragments and transfer them to another cell. What is the significance of using a filter in the transduction experiment?
The filter prevented direct cell-to-cell contact, proving that DNA transfer was mediated by something small enough to pass through, such as a virus. How does the activation of a transducer in specialized transduction occur?
Activation can be triggered by chemicals, another virus, or other stimuli, causing the transducer to excise and take nearby genes for transfer.
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