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Ch. 4 - Gene Interaction
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
All textbooksSanders 3rd EditionCh. 4 - Gene InteractionProblem 12b
Chapter 4, Problem 12b

Using the information provided in Problems 10 and 11, determine the genotype and phenotype of parents that produce the following progeny:
3/8 black : 3/8 cream : 2/8 albino

Verified step by step guidance
1
Analyze the phenotypic ratio of the progeny (3/8 black : 3/8 cream : 2/8 albino) and determine if it corresponds to a specific genetic inheritance pattern, such as dihybrid crosses or epistasis.
Assign symbols to the alleles for the traits involved. For example, let 'B' and 'b' represent one gene pair, and 'C' and 'c' represent another gene pair. Define the phenotypes associated with each genotype (e.g., BB or Bb = black, bb = cream, cc = albino).
Use the phenotypic ratio to infer the genotypes of the parents. For example, if the ratio suggests a dihybrid cross with epistasis, the parents might be heterozygous for both genes (e.g., BbCc x BbCc).
Set up a Punnett square for the parental genotypes to confirm that the expected phenotypic ratio matches the observed progeny ratio. Include all possible combinations of alleles and their corresponding phenotypes.
Verify that the calculated phenotypic ratio from the Punnett square (e.g., 3/8 black : 3/8 cream : 2/8 albino) matches the observed progeny ratio. Adjust the parental genotypes if necessary to achieve consistency.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Genotype

Genotype refers to the genetic constitution of an organism, specifically the alleles it possesses for a particular trait. In this context, understanding the genotype is crucial for determining how specific combinations of alleles can lead to the observed phenotypic ratios in the progeny. For example, if black and cream are dominant traits, the genotypes of the parents must reflect this dominance to produce the given ratios.
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Phenotype

Phenotype is the observable physical or biochemical characteristics of an organism, determined by both its genotype and environmental influences. In the question, the phenotypic ratios of black, cream, and albino progeny indicate how the traits are expressed. Analyzing these ratios helps infer the possible genotypes of the parents that could yield such offspring.
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Punnett Square

A Punnett Square is a diagram used to predict the genotypes of offspring from a cross between two parents. It allows for the visualization of how alleles segregate and combine during reproduction. By setting up a Punnett Square with the potential genotypes of the parents, one can calculate the expected phenotypic ratios, which is essential for solving the problem presented.
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Related Practice
Textbook Question

In the rats identified in Problem 10, a third independently assorting gene involved in the determination of coat color is the C gene. At this locus, the genotype C– permits expression of pigment from genes B and D. The cc genotype, however, prevents expression of coat color and results in albino rats. For each of the following crosses, determine the expected phenotype ratio of progeny.

bbDDCc×BBddCc

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Textbook Question

In the rats identified in Problem 10, a third independently assorting gene involved in the determination of coat color is the C gene. At this locus, the genotype C– permits expression of pigment from genes B and D. The cc genotype, however, prevents expression of coat color and results in albino rats. For each of the following crosses, determine the expected phenotype ratio of progeny.

BbDdCC×BbDdCC

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Textbook Question

Using the information provided in Problems 10 and 11, determine the genotype and phenotype of parents that produce the following progeny:

9/16 brown : 3/16 black : 4/16 albino

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Textbook Question

Using the information provided in Problems 10 and 11, determine the genotype and phenotype of parents that produce the following progeny:

27/64 brown : 16/64 albino : 9/64 yellow : 9/64 black : 3/64 cream

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Textbook Question

Using the information provided in Problems 10 and 11, determine the genotype and phenotype of parents that produce the following progeny:

3/4 brown : 1/4 yellow

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Textbook Question

Total cholesterol in blood is reported as the number of milligrams (mg) of cholesterol per 100 milliliters (mL) of blood. The normal range is 180–220 mg/100 mL. A gene mutation altering the function of cell-surface cholesterol receptors restricts the ability of cells to collect cholesterol from blood and draw it into cells. This defect results in elevated blood cholesterol levels. Individuals who are heterozygous for a mutant allele and a wild-type allele have levels of 300–600 mg/100 mL, and those who are homozygous for the mutation have levels of 800–1000 mg/100 mL. Identify the genetic term that best describes the inheritance of this form of elevated cholesterol level, and justify your choice.

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