Textbook Question
Suppose an F₁ dihybrid (round yellow plant from Problem 16) is crossed to the pure-breeding green, round parental strain. Use a forked-line diagram to predict the phenotypic distribution of the resulting progeny.
Ch. 2 - Transmission Genetics
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
Chapter 2, Problem 16b
A geneticist crosses a pure-breeding strain of peas producing yellow, wrinkled seeds with one that is pure-breeding for green, round seeds.
What proportion of the F₂ progeny are expected to have yellow seeds? Wrinkled seeds? Green seeds? Round seeds?
Verified step by step guidance1
Step 1: Identify the traits and their inheritance patterns. Yellow and green seed color are determined by one gene, and round and wrinkled seed shape are determined by another gene. Assume Mendelian inheritance where one allele is dominant and the other is recessive for each trait.
Step 2: Assign alleles to the traits. Let 'Y' represent the dominant allele for yellow seeds and 'y' represent the recessive allele for green seeds. Similarly, let 'R' represent the dominant allele for round seeds and 'r' represent the recessive allele for wrinkled seeds.
Step 3: Determine the genotypes of the parental strains. The pure-breeding yellow, wrinkled strain will have the genotype YYrr, and the pure-breeding green, round strain will have the genotype yyRR.
Step 4: Perform a dihybrid cross to determine the F₁ generation. Cross YYrr with yyRR. The F₁ progeny will all be heterozygous for both traits (YyRr), producing yellow, round seeds due to the dominance of 'Y' and 'R'.
Step 5: Use a Punnett square to analyze the F₂ generation. Cross two F₁ individuals (YyRr × YyRr) to determine the proportions of each phenotype. Calculate the expected proportions for yellow seeds, wrinkled seeds, green seeds, and round seeds based on the combinations of alleles in the Punnett square.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Mendelian Genetics
Mendelian genetics is the study of how traits are inherited through generations, based on the principles established by Gregor Mendel. It involves understanding dominant and recessive alleles, where dominant traits mask the expression of recessive ones. In this case, yellow seeds (dominant) and green seeds (recessive) are key traits in the pea plants being studied.
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Descriptive Genetics
Punnett Square
A Punnett square is a diagram used to predict the genotypic and phenotypic ratios of offspring from a genetic cross. By organizing the alleles of the parent plants, it allows for a visual representation of how traits may combine in the F1 and F2 generations. This tool is essential for determining the expected proportions of yellow, green, wrinkled, and round seeds in the progeny.
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Phenotypic Ratios
Phenotypic ratios refer to the relative frequencies of different phenotypes in the offspring resulting from a genetic cross. In this scenario, the F2 generation will exhibit a specific ratio of yellow to green seeds and wrinkled to round seeds based on the inheritance patterns. Understanding these ratios helps predict the expected traits in the progeny from the initial cross.
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Related Practice
Textbook Question
A geneticist crosses a pure-breeding strain of peas producing yellow, wrinkled seeds with one that is pure-breeding for green, round seeds.
What is the expected phenotype distribution among the F₂ progeny?
Textbook Question
The accompanying pedigree shows the transmission of albinism (absence of skin pigment) in a human family.
What is the probability that female I-3 is a heterozygous carrier of the allele for albinism?
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Textbook Question
The accompanying pedigree shows the transmission of albinism (absence of skin pigment) in a human family.
One child of female I-3 has albinism. What is the probability that any of the other four children are carriers of the allele for albinism?
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Textbook Question
In pea plants, the appearance of flowers along the main stem is a dominant phenotype called 'axial' and is controlled by an allele T. The recessive phenotype, produced by an allele t, has flowers only at the end of the stem and is called 'terminal.' Pod form displays a dominant phenotype, 'inflated,' controlled by an allele C, and a recessive 'constricted' form, produced by the c allele. A cross is made between a pure-breeding axial, constricted plant and a plant that is pure-breeding terminal, inflated.
The F₁ progeny of this cross are allowed to self-fertilize. What is the expected phenotypic distribution among the F₂ progeny?
Textbook Question
A geneticist crosses a pure-breeding strain of peas producing yellow, wrinkled seeds with one that is pure-breeding for green, round seeds.
Use a Punnett square to predict the F₂ progeny that would be expected if the F₁ are allowed to self-fertilize.