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Ch. 3 - Mendelian Genetics
Klug - Concepts of Genetics 12th Edition
Klug12th EditionConcepts of Genetics ISBN: 9780135564776Not the one you use?Change textbook
All textbooksKlug 12th EditionCh. 3 - Mendelian GeneticsProblem 13
Chapter 3, Problem 13

How many different types of gametes can be formed by individuals of the following genotypes:
(a) AaBb
(b) AaBB
(c) AaBbCc
(d) AaBBcc
(e) AaBbcc
(f) AaBbCcDdEe
What are the gametes in each case?

Verified step by step guidance
1
Understand that the number of different types of gametes an individual can produce depends on the number of heterozygous gene pairs they have. Each heterozygous gene pair (e.g., Aa) can produce 2 types of alleles (A or a) in the gametes.
Use the formula for the number of different gametes: \$2^n\(, where \)n$ is the number of heterozygous gene pairs in the genotype.
For each genotype, identify the heterozygous gene pairs (e.g., Aa, Bb, Cc, Dd, Ee) and count them to find \(n\).
Calculate the number of different gametes by raising 2 to the power of \(n\) (i.e., \$2^n$).
List the possible gametes by combining one allele from each gene pair. For homozygous pairs (e.g., BB or cc), only one allele type is possible, so they do not increase the number of gamete types.

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Key Concepts

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

Mendelian Genetics and Allele Segregation

Mendelian genetics explains how alleles segregate during gamete formation. Each gene has two alleles, and during meiosis, these alleles separate so that each gamete receives only one allele per gene. This principle helps predict the variety of gametes an organism can produce based on its genotype.
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Independent Assortment of Genes

Independent assortment states that alleles of different genes segregate independently during gamete formation. This means the combination of alleles for one gene does not affect the combination for another, increasing the diversity of possible gametes. It applies when genes are on different chromosomes or far apart on the same chromosome.
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Calculating Number and Types of Gametes

The number of different gametes is calculated as 2^n, where n is the number of heterozygous gene pairs. Homozygous gene pairs contribute only one allele type, so they do not increase gamete variety. Listing gametes involves combining one allele from each gene pair in all possible ways.
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Related Practice
Textbook Question

In Drosophila, gray body color is dominant to ebony body color, while long wings are dominant to vestigial wings. Assuming that the P₁ individuals are homozygous, work the following crosses through the F₂ generation, and determine the genotypic and phenotypic ratios for each generation.

gray, long x ebony, vestigial

1560
views
Textbook Question

In Drosophila, gray body color is dominant to ebony body color, while long wings are dominant to vestigial wings. Assuming that the P₁ individuals are homozygous, work the following crosses through the F₂ generation, and determine the genotypic and phenotypic ratios for each generation.

gray, vestigial x ebony, long

421
views
Textbook Question

In Drosophila, gray body color is dominant to ebony body color, while long wings are dominant to vestigial wings. Assuming that the P₁ individuals are homozygous, work the following crosses through the F₂ generation, and determine the genotypic and phenotypic ratios for each generation.

gray, long x gray, vestigial.

458
views
Textbook Question

Mendel crossed peas having green seeds with peas having yellow seeds. The F₁ generation produced only yellow seeds. In the F₂, the progeny consisted of 6022 plants with yellow seeds and 2001 plants with green seeds. Of the F₂ yellow-seeded plants, 519 were self-fertilized with the following results: 166 bred true for yellow and 353 produced an F₃ ratio of 3/4 yellow: 1/4 green. Explain these results by diagramming the crosses.

551
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Textbook Question

In a study of black guinea pigs and white guinea pigs, 100 black animals were crossed with 100 white animals, and each cross was carried to an F₂ generation. In 94 of the crosses, all the F₁ offspring were black and an F₂ ratio of 3 black:1 white was obtained. In the other 6 cases, half of the F₁ animals were black and the other half were white. Why? Predict the results of crossing the black and white F₁ guinea pigs from the 6 exceptional cases.

552
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Textbook Question

Mendel crossed peas having round green seeds with peas having wrinkled yellow seeds. All F₁ plants had seeds that were round and yellow. Predict the results of testcrossing these F₁ plants.

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