Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination

Sanders - Genetic Analysis: An Integrated Approach 3rd Edition

Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172당신이 사용하는 게 아니라요?교과서 변경

Sanders 3rd Edition

Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination

문제 40b

11장, 문제 40b

Common baker's yeast (Saccharomyces cerevisiae) is normally grown at 37°C, but it will grow actively at temperatures down to approximately 25°C. A haploid culture of wild-type yeast is mutagenized with EMS. Cells from the mutagenized culture are spread on a complete-medium plate and grown at 25°C. Six colonies (1 to 6) are selected from the original complete-medium plate and transferred to two fresh complete-medium plates. The new complete plates (shown) are grown at 25°C and 37°C. Four replica plates are made onto minimal medium or minimal plus adenine from the 25°C complete-medium plate. The new plates are grown at either 25°C or 37°C and the growth results are shown.

Classify the nature of the mutations in colonies 1, 2, and 5.

검증된 단계별 안내

Step 1: Understand the experimental setup. The yeast cells were mutagenized using EMS (ethyl methanesulfonate), which induces point mutations. The colonies were grown under different conditions (temperature and media) to observe their growth patterns. The goal is to classify the mutations based on these observations.

Step 2: Analyze the growth results for colonies 1, 2, and 5. Look at the growth patterns on complete medium at 25°C and 37°C, as well as on minimal medium and minimal medium plus adenine at both temperatures. This will help determine if the mutations affect temperature sensitivity or nutrient requirements.

Step 3: Determine if the mutations are temperature-sensitive. If a colony grows at 25°C but not at 37°C, it suggests a temperature-sensitive mutation affecting a gene required for growth at higher temperatures.

Step 4: Assess nutrient requirements. If a colony grows on minimal medium plus adenine but not on minimal medium alone, it indicates an adenine auxotrophy mutation, meaning the colony requires adenine supplementation to grow.

Step 5: Classify the mutations. Based on the growth patterns, assign the nature of the mutations for colonies 1, 2, and 5. For example, a colony that is temperature-sensitive and adenine auxotrophic would have both types of mutations. Use the data provided to make these classifications.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Mutagenesis

Mutagenesis is the process by which the genetic information of an organism is changed, resulting in a mutation. In this context, the wild-type yeast is treated with EMS (ethyl methanesulfonate), a chemical mutagen that induces random mutations in the DNA. Understanding mutagenesis is crucial for analyzing the resulting phenotypes of the yeast colonies, as it helps to identify whether the mutations are beneficial, neutral, or harmful.

Haploid Organisms

Haploid organisms, like the yeast Saccharomyces cerevisiae, have a single set of chromosomes, which simplifies the analysis of genetic mutations. In haploids, any mutation will directly affect the phenotype since there is no second allele to mask its effects. This characteristic makes haploid yeast an excellent model organism for studying gene function and mutation effects, particularly in experiments involving mutagenesis.

Phenotypic Analysis

Phenotypic analysis involves observing and classifying the physical and functional traits of organisms resulting from their genetic makeup. In this experiment, the growth of yeast colonies at different temperatures and on various media allows researchers to determine the nature of mutations present in colonies 1, 2, and 5. By comparing growth patterns, researchers can infer whether mutations are related to temperature sensitivity or nutrient utilization, which is essential for classifying the mutations.

관련 실천

교과서 질문

Thinking back to the discussion of gain-of-function and loss-of-function mutations, explain why gain-of-function mutations are often dominant and why loss-of-function mutations are often recessive. Give an example of a type of gain-of-function mutation that is dominant and of a loss-of-function mutation that is recessive.

734

views

교과서 질문

Considering the Dumbo mutation in Problem 37, what kinds of additional evidence would help you determine whether Dumbo is a mutation of a regulatory sequence or of a protein-coding gene?

439

views

교과서 질문

The two gels illustrated contain dideoxynucleotide DNA-sequencing information for a wild-type segment and mutant segment of DNA corresponding to the N-terminal end of a protein. The start codon and the next five codons are sequenced.

Write the DNA sequence of both alleles, including strand polarity.

554

views

교과서 질문

Identify the template and nontemplate strands of DNA.

605

views

교과서 질문

Common baker's yeast (Saccharomyces cerevisiae) is normally grown at 37°C, but it will grow actively at temperatures down to approximately 25°C. A haploid culture of wild-type yeast is mutagenized with EMS. Cells from the mutagenized culture are spread on a complete-medium plate and grown at 25°C. Six colonies (1 to 6) are selected from the original complete-medium plate and transferred to two fresh complete-medium plates. The new complete plates (shown) are grown at 25°C and 37°C. Four replica plates are made onto minimal medium or minimal plus adenine from the 25°C complete-medium plate. The new plates are grown at either 25°C or 37°C and the growth results are shown.

Which colonies are prototrophic and which are auxotrophic? What growth information is used to make these determinations?

609

views

교과서 질문

Common baker's yeast (Saccharomyces cerevisiae) is normally grown at 37°C, but it will grow actively at temperatures down to approximately 25°C. A haploid culture of wild-type yeast is mutagenized with EMS. Cells from the mutagenized culture are spread on a complete-medium plate and grown at 25°C. Six colonies (1 to 6) are selected from the original complete-medium plate and transferred to two fresh complete-medium plates. The new complete plates (shown) are grown at 25°C and 37°C. Four replica plates are made onto minimal medium or minimal plus adenine from the 25°C complete-medium plate. The new plates are grown at either 25°C or 37°C and the growth results are shown.

What can you say about colony 4?

1034

views