Concept explainers
You will need to refer to question 2 in More Genetic TIPS to answer this question. The gene for coat color in rabbits can exist in four alleles termed C(full coat color),
Assume that C is dominant to the other three alleles,
A. What is the frequency of albino rabbits?
B. Among 1000 rabbits, how many would you expect to have a Himalayan coat color?
C. Among 1000 rabbits, how many would be heterozygotes with a chinchilla coat color?
To review:
In a population of rabbits in Hardy-Weinberg equilibrium, determinethe:
Frequency of albino rabbits
Number of rabbits to have a Himalayan coat color
Number of rabbits to be heterozygous with a chinchilla coat color
Introduction:
The Hardy-Weinberg equilibrium is a principle, which states that in a given population, the frequency of occurrence of alleles of a gene or a locus can be determined. The frequency is supposed to remain fixed and even remain the same throughout the generation. In other words, the principle says that allele frequency in a population is stable and is constant from generation to generation.
Explanation of Solution
The Hardy- Weinberg equation in its standard form (two-allele) indicates that each individual inherits two copies of each gene, one from each parent. For a two-allele condition, it can also be expressed as
This equation can be expanded to include three or more than three alleles. For the given situation in the question, there a gene exists as four alleles: C(full coat color), cch (chinchilla), ch (Himalayan), and c (albino). The allele frequency of C is designated by the letter p, cch by the letter q, ch by the letter r, and c by the letter s.The allele frequencies are listed below:
Under these conditions, the Hardy- Weinberg equation can be written as follows:
where,
p2 is the genotype of the frequency of CC
q2 is the genotype frequency of cchcch
r2 is the genotype frequency of chch
s2 is the genotype frequency of cc
2pq is the genotype frequency of Ccch
2qr is the genotype frequency of cchch
2pr is the genotype frequency of Cch
2ps is the genotype frequency of Cc
2rs is the genotype frequency of chc
2qs is the genotype frequency of cchc
Now,
The frequency of albino rabbits is s2, which is equal to 0.0025 or 0.25%.\
C.
The number of rabbits that are heterozygotes with chinchilla coat color among 1000 rabbits can be calculated as follows:
Therefore, it can be concluded that the frequency of the albino rabbits is 0.0025 or 0.25%.The number of rabbits with a Himalayan coat color would be 237 (approx.).The number of rabbits that are heterozygotes with chinchilla coat color would be 166 (approx.).
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Chapter 27 Solutions
Genetics: Analysis and Principles
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