Textbook Question
Epistatic gene interaction results in a modification of the F₂ dihybrid ratio.
What is the expected F₂ ratio?
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Ch. 4 - Gene Interaction
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 4, Problem 38a
Draw a pedigree containing two parents and four children. Both of the parents have AB blood type. The first child is type A, the second child is type AB, and the third child is type B.
Assign the genotypes to these five people.
Verified step by step guidance1
Start by understanding the ABO blood group system. Blood type is determined by the ABO gene, which has three alleles: IA, IB, and i. IA and IB are codominant, meaning both are expressed when present together, while i is recessive.
Assign the genotypes of the parents. Since both parents have AB blood type, their genotypes must be IAIB. This means each parent can pass on either the IA or IB allele to their offspring.
Determine the possible genotypes of the children. Use a Punnett square to cross the IAIB genotypes of the parents. The possible combinations are: IAIA (Type A), IAIB (Type AB), IBIB (Type B), and IAi or IBi (Type A or B, but i is not relevant here since all children have A, AB, or B types).
Assign the genotypes to the children based on their blood types: - The first child is Type A, so their genotype must be IAIA. - The second child is Type AB, so their genotype must be IAIB. - The third child is Type B, so their genotype must be IBIB.
Draw the pedigree. Represent the parents as a male (square) and female (circle) connected by a horizontal line. Below them, draw four vertical lines leading to the children (circles or squares depending on gender). Label each individual with their blood type and genotype: Parents (IAIB), First child (IAIA), Second child (IAIB), Third child (IBIB).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Blood Type Inheritance
Blood type is determined by the ABO gene, which has three alleles: A, B, and O. The A and B alleles are co-dominant, meaning that if both are present, the individual will have type AB blood. The O allele is recessive, so an individual must inherit two O alleles to have type O blood. Understanding these inheritance patterns is crucial for predicting the blood types of offspring based on parental genotypes.
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Types of Maternal Inheritance
Genotype and Phenotype
The genotype refers to the genetic makeup of an individual, while the phenotype is the observable expression of that genotype. For blood types, the genotype can be AA, AO, BB, BO, AB, or OO, which correspond to the phenotypes A, B, AB, and O. Knowing the genotypes of the parents allows us to predict the possible phenotypes of their children.
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Pedigree Analysis
A pedigree is a diagram that depicts the genetic relationships and inheritance patterns within a family. It uses standardized symbols to represent individuals and their phenotypes, allowing for the visualization of how traits are passed down through generations. Analyzing a pedigree helps in understanding the likelihood of certain traits appearing in offspring based on the genotypes of the parents.
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Related Practice
Textbook Question
Epistatic gene interaction results in a modification of the F₂ dihybrid ratio.
What genetic principle is the basis of this expected F₂ ratio?
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Textbook Question
Epistatic gene interaction results in a modification of the F₂ dihybrid ratio.
Give two examples of modified F₂ ratios produced by epistatic gene interactions and describe how gene interaction results in the ratios.
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Textbook Question
Draw a pedigree containing two parents and four children. Both of the parents have an AB blood type. The first child is type A, the second child is type AB, and the third child is type B.
The fourth child tests as having blood type O, which is not possible given the parental genotypes. Look at the Figure below and read the description of the molecular process that generates ABO blood group antigens. What other mutation could account for this observation?
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Textbook Question
Draw a pedigree containing two parents and four children. Both of the parents have AB blood type. The first child is type A, the second child is type AB, and the third child is type B.
What is the name of the genetic phenomenon producing this observation?
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