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Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Sanders 3rd EditionCh. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages문제 25a
6장, 문제 25a

Define the term genetic complementation.
Describe how the term applies to an experiment in which two lysis-defective bacteriophages are able to coinfect a bacterial cell and produce lysis.

검증된 단계별 안내
1
Genetic complementation is a phenomenon where two different mutations in the genome of an organism or virus can complement each other when present in the same cell, restoring a normal phenotype. This occurs when the mutations affect different genes or functional regions, allowing the functional product of one gene to compensate for the defect in the other.
In the context of bacteriophages, genetic complementation can be studied by coinfecting a bacterial cell with two lysis-defective bacteriophages, each carrying a mutation that prevents them from lysing the host cell independently.
To determine if genetic complementation occurs, observe whether the coinfection results in lysis of the bacterial cell. If lysis occurs, it suggests that the two bacteriophages are complementing each other, meaning their mutations affect different genes or functional regions required for lysis.
Design the experiment by ensuring that the two bacteriophages are introduced into the same bacterial cell under controlled conditions. Monitor the bacterial culture for signs of lysis, such as clearing of the bacterial lawn or reduction in turbidity.
Interpret the results: If lysis is observed, it indicates genetic complementation. If no lysis occurs, it suggests that the mutations are in the same gene or functional region, and complementation is not possible.

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주요 개념

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Genetic Complementation

Genetic complementation occurs when two different mutations in a gene are present in the same organism, and the normal function is restored. This phenomenon is often observed in diploid organisms, where one allele can compensate for the defective allele of another. In the context of bacteriophages, it allows for the production of functional proteins necessary for lysis when two defective phages infect the same bacterial cell.
추천 영상:
가이드 코스
05:05
Complementation

Bacteriophage Coinfection

Bacteriophage coinfection refers to the simultaneous infection of a bacterial cell by two or more bacteriophages. This process can lead to genetic interactions between the phages, such as complementation, where the presence of different defective phages can result in the production of functional viral components. Coinfection is a powerful tool in virology to study genetic interactions and the mechanisms of viral replication.
추천 영상:
가이드 코스
06:04
Mapping Bacteriophages

Lysis in Bacteriophages

Lysis is the process by which a bacteriophage causes the destruction of a bacterial cell, releasing new viral particles. This process typically involves the production of lytic enzymes that break down the bacterial cell wall. In the case of lysis-defective bacteriophages, the inability to lyse the host cell can be overcome through complementation when two different phages infect the same cell, allowing for the production of the necessary lytic components.
추천 영상:
가이드 코스
06:04
Mapping Bacteriophages
관련 실천
교과서 질문

Define the term genetic complementation.

Give another example of genetic complementation and describe how genetic complementation works in that case.

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교과서 질문

Look closely at the consolidated Hfr map and the data used to build the map on page 261. Suppose a fifth Hfr strain had the F factor inserted exactly halfway between cysE and leuU and had an orientation that was the same as that of Hfr 1. List the order of gene transfer for the first six genes transferred by this Hfr and the number of minutes of conjugation at which each gene is expected to be seen.


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교과서 질문

The phage P1 is used as a generalized transducing phage in an experiment combining a donor strain of E. coli of genotype leu⁺ phe⁺ ala⁺ and a recipient strain that is leu⁻ phe⁻ ala⁻. In separate experiments, transductants are selected for leu⁺ (Experiment A), for ala⁺ (Experiment B), and for phe⁺ (Experiment C). Following selection, transductant genotypes for the unselected markers are identified. The selection experiment results below show the frequency of each genotype.

In Experiment B, why are there no transductants with the genotype leu⁻ ala⁺?

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교과서 질문

Devise an experiment to identify bacteria that are auxotrophic and unable to produce two amino acids, lysine (lys) and valine (val). The auxotrophic bacteria are in a pool of bacteria in which all the other bacteria are prototrophic. The genotype of the auxotrophs is lys⁻ val⁻. Describe each step in the experiment, identify the constituents in any growth medium or growth plates you propose, and identify the results that will conclusively identify bacteria that are lys⁻ val⁻.

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교과서 질문

The phage P1 is used as a generalized transducing phage in an experiment combining a donor strain of E. coli of genotype leu⁺ phe⁺ ala⁺ and a recipient strain that is leu⁻ phe⁻ ala⁻. In separate experiments, transductants are selected for leu⁺ (Experiment A), for ala⁺ (Experiment B), and for phe⁺ (Experiment C). Following selection, transductant genotypes for the unselected markers are identified. The selection experiment results below show the frequency of each genotype.

Diagram the crossover events that form each of the transductants in Experiment A.

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