Textbook Question
A fragment of a wild-type polypeptide is sequenced for seven amino acids. The same polypeptide region is sequenced in four mutants.
Identify the mutation that produces each mutant polypeptide.
Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172
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Table of contents
- Ch. 1 - The Molecular Basis of Heredity, Variation, and Evolution64
- Ch. 2 - Transmission Genetics144
- Ch. 3 - Cell Division and Chromosome Heredity81
- Ch. 4 - Gene Interaction87
- Ch. 5 - Genetic Linkage and Mapping in Eukaryotes103
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages73
- Ch. 7 - DNA Structure and Replication71
- Ch. 8 - Molecular Biology of Transcription and RNA Processing79
- Ch. 9 - The Molecular Biology of Translation110
- Ch. 10 - Eukaryotic Chromosome Abnormalities and Molecular Organization100
- Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination86
- Ch. 12 - Regulation of Gene Expression in Bacteria and Bacteriophage90
- Ch. 13 - Regulation of Gene Expression in Eukaryotes38
- Ch. 14 - Analysis of Gene Function via Forward Genetics and Reverse Genetics72
- Ch. 15 - Recombinant DNA Technology and Its Applications69
- Ch. 16 - Genomics: Genetics from a Whole-Genome Perspective49
- Ch. 17 - Organelle Inheritance and the Evolution of Organelle Genomes27
- Ch. 18 - Developmental Genetics43
- Ch. 19 - Genetic Analysis of Quantitative Traits66
- Ch. 20 - Population Genetics and Evolution at the Population, Species, and Molecular Levels105
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
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Sanders 3rd EditionCh. 11 - Gene Mutation, DNA Repair, and Homologous RecombinationProblem 29e
Sanders 3rd EditionCh. 11 - Gene Mutation, DNA Repair, and Homologous RecombinationProblem 29eChapter 11, Problem 29e
A wild-type culture of haploid yeast is exposed to ethyl methanesulfonate (EMS). Yeast cells are plated on a complete medium, and 6 colonies (colonies numbered 1 to 6) are transferred to a new complete medium plate for further study. Four replica plates are made from the complete medium plate to plates containing minimal medium or minimal medium plus one amino acid (replica plates numbered 1 to 4) with the following results:
Are there any colonies for which genotype information cannot be determined? If so, which colony or colonies?
Verified step by step guidance1
Step 1: Understand the experimental setup. A wild-type haploid yeast culture was mutagenized with EMS and plated on complete medium. Six colonies were selected and replica plated onto four different media: minimal medium, minimal + histidine, minimal + arginine, and minimal + leucine. Growth or no growth on these plates indicates whether the colonies require supplementation for specific amino acids.
Step 2: Analyze growth on the minimal medium (Plate 1). Colonies that grow on minimal medium are prototrophic (do not require supplementation), while those that do not grow are auxotrophic (require supplementation). From the image, colonies 1 and 4 grow on minimal medium, so they are prototrophic; colonies 2, 3, 5, and 6 do not grow, indicating auxotrophy.
Step 3: Analyze growth on minimal + histidine (Plate 2). Colonies that grow here but not on minimal medium are likely histidine auxotrophs. Colonies 1 and 4 grow here (consistent with prototrophy), colony 3 grows here but not on minimal medium, indicating it is a histidine auxotroph. Colony 2 does not grow here, so it is not rescued by histidine.
Step 4: Analyze growth on minimal + arginine (Plate 3). Colonies 1, 2, and 4 grow here. Colony 2 grows here but not on minimal or minimal + histidine, indicating it is an arginine auxotroph. Colonies 3, 5, and 6 do not grow here.
Step 5: Analyze growth on minimal + leucine (Plate 4). Colonies 1, 4, and 5 grow here. Colony 5 grows only on minimal + leucine, indicating it is a leucine auxotroph. Colony 6 does not grow on any plate except complete medium, so its genotype cannot be determined from this data because it does not grow on any minimal or supplemented medium.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Replica Plating Technique
Replica plating is a method used to transfer colonies from one plate to multiple plates with different media. It helps identify mutants by comparing growth patterns on selective versus non-selective media, revealing nutritional requirements or auxotrophies.
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Auxotrophic Mutations in Yeast
Auxotrophic mutations cause yeast cells to lose the ability to synthesize specific nutrients, requiring supplementation for growth. By testing growth on minimal media plus specific amino acids, one can determine which nutrient the mutant cannot produce.
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10:48Mutations and Phenotypes
Interpreting Growth Patterns for Genotype Determination
Growth or no growth on minimal and supplemented media indicates the genotype of yeast colonies. Colonies growing only on supplemented media are auxotrophs for that nutrient, while those growing on minimal media are prototrophs. Ambiguous or inconsistent growth complicates genotype identification.
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Related Practice
Textbook Question
A wild-type culture of haploid yeast is exposed to ethyl methanesulfonate (EMS). Yeast cells are plated on a complete medium, and 6 colonies (colonies numbered 1 to 6) are transferred to a new complete medium plate for further study. Four replica plates are made from the complete medium plate to plates containing minimal medium or minimal medium plus one amino acid (replica plates numbered 1 to 4) with the following results:
For colonies 1, 3, and 5, write '+' for the wild-type synthesis and '−' for the mutant synthesis of histidine and leucine.
Textbook Question
A wild-type culture of haploid yeast is exposed to ethyl methanesulfonate (EMS). Yeast cells are plated on a complete medium, and 6 colonies (colonies numbered 1 to 6) are transferred to a new complete medium plate for further study. Four replica plates are made from the complete medium plate to plates containing minimal medium or minimal medium plus one amino acid (replica plates numbered 1 to 4) with the following results:
Identify any colonies that are his⁻, arg⁻, leu⁻.
Textbook Question
A fragment of a wild-type polypeptide is sequenced for seven amino acids. The same polypeptide region is sequenced in four mutants.
Use the available information to characterize each mutant.
Textbook Question
A fragment of a wild-type polypeptide is sequenced for seven amino acids. The same polypeptide region is sequenced in four mutants.
Determine the wild-type mRNA sequence.
Textbook Question
A wild-type culture of haploid yeast is exposed to ethyl methanesulfonate (EMS). Yeast cells are plated on a complete medium, and 6 colonies (colonies numbered 1 to 6) are transferred to a new complete medium plate for further study. Four replica plates are made from the complete medium plate to plates containing minimal medium or minimal medium plus one amino acid (replica plates numbered 1 to 4) with the following results:
Identify the colonies that are auxotrophic (mutant). What growth information leads to your answer?