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Still referring to Problem 1, what will be the possible genotypes of offspring from the following matings? With what frequency will each genotype show up?
- a. AABB × aaBB
- b. AaBB × AABb
- c. AaBb × aabb
- d. AaBb × AaBb
a.
To predict: The predicted genotype frequencies among the offspring for the mating AABB × aaBB.
Introduction: The law of independent assortment and law of segregation are the laws proposed by Gregor Johann Mendel, a geneticist. Mendel proposed the law of independent assortment based on the results of monohybrid cross that “two alleles at any locus tend to separate from each other during meiosis, so they end up in different gametes”. Mendel proposed the law of independent assortment based on the results of dihybrid cross that “alleles at one locus tend to assort into gametes independently of alleles at other loci”. The number of possible allele combination for the given genotype is given by the formula 2n where “n” is the number of heterozygous alleles that are present.
Explanation of Solution
A monohybrid cross is constructed with Punnett square for the parents having the genotype AABB and aaBB.
All the offspring have the same genotype AaBB. Therefore, there is no genotype frequency.
b.
To predict: The predicted genotype frequencies among the offspring for the mating AaBB × AABb.
Introduction: The law of independent assortment and law of segregation are the laws proposed by Gregor Johann Mendel, a geneticist. Mendel proposed the law of independent assortment based on the results of monohybrid cross that “two alleles at any locus tend to separate from each other during meiosis, so they end up in different gametes”. Mendel proposed the law of independent assortment based on the results of dihybrid cross that “alleles at one locus tend to assort into gametes independently of alleles at other loci”. The number of possible allele combination for the given genotype is given by the formula 2n where “n” is the number of heterozygous alleles that are present.
Explanation of Solution
A monohybrid cross is constructed with Punnett square for the parents having the genotype AaBB and AABb.
The following is the frequency of genotypes.
Total number of possible genotypes = 4.
AABB=
AABb=
AaBB=
AaBb =
The frequency of all four genotypes is 25%.
c.
To predict: The predicted genotype frequencies among the offspring for the mating AaBb × aabb.
Introduction: The law of independent assortment and law of segregation are the laws proposed by Gregor Johann Mendel, a geneticist. Mendel proposed the law of independent assortment based on the results of monohybrid cross that “two alleles at any locus tend to separate from each other during meiosis, so they end up in different gametes”. Mendel proposed the law of independent assortment based on the results of dihybrid cross that “alleles at one locus tend to assort into gametes independently of alleles at other loci”. The number of possible allele combination for the given genotype is given by the formula 2n where “n” is the number of heterozygous alleles that are present.
Explanation of Solution
A monohybrid cross is constructed with Punnett square for the parents having the genotype AaBb and aabb
The following is the frequency of genotypes.
Total number of possible genotypes = 4.
AABB=
aaBB=
Aabb=
aabb =
The frequency of all four genotypes is 25%.
d.
To predict: The predicted genotype frequencies among the offspring for the mating AaBb × AaBb.
Introduction: The law of independent assortment and law of segregation are the laws proposed by Gregor Johann Mendel, a geneticist. Mendel proposed the law of independent assortment based on the results of monohybrid cross that “two alleles at any locus tend to separate from each other during meiosis, so they end up in different gametes”. Mendel proposed the law of independent assortment based on the results of dihybrid cross that “alleles at one locus tend to assort into gametes independently of alleles at other loci”. The number of possible allele combination for the given genotype is given by the formula 2n where “n” is the number of heterozygous alleles that are present.
Explanation of Solution
A monohybrid cross is constructed with Punnett square for the parents having the genotype AaBb and AaBb.
The following is the frequency of genotypes.
Total number of possible genotypes = 16.
AABB=
AABb=
AaBB=
AaBb=
AAbb=
Aabb=
aaBB=
aaBb=
aabb=
The frequency of genotypes AABB, aaBB , AAbb and aabb is 6.25%.
The frequency of genotypes AaBB, AABb, aaBb and Aabb is 12.5%.
The frequency of genotypes AaBb is 25%.
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Chapter 19 Solutions
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