Post-lab Questions 1. Explain the implications of Mendel\'s law of gametes. segr
ID: 132025 • Letter: P
Question
Post-lab Questions 1. Explain the implications of Mendel's law of gametes. segregation as it applies to the distribution of alleles in 2. Assume that production of hairs on a plant's leaves is controlled by a single gene wit (dominant) and h (recessive). Hairy leaves are dominant to smooth (non-hairy) leaves. h two alleles H ic a. Name the genotype(s) of a smooth-leaved plant. b. Name the genotypelfs) of a hairy-leaved plant. c. What are the possible genotypes of gametes produced by the smooth-leaved plant? d. What are the possible genotypes of gametes produced by the hairy-leaved plant? 3. Suppose you have two traits controlled by genes on separate chromosomes. If sexual reproduction occurs between two heterozygous parents, what is the genotypic ratio of all possible gametes produced by this dihybrid cross? 4. Suppose students in previous semesters had removed some of the corn kernels from the genetic corn ears before you counted them. What effect would this have on your results? Wihr ffm 5. Assume that one allele is completely dominant over the other for the following questions. a. Two individuals heterozygous for a single trait have children. What is the expected phenotypic ratio the possible offspring? b. Two individuals heterozygous for two traits have children. What would be the expected phenotyp ratio of the possible offspring? 208Explanation / Answer
Answer 1 Mendel's law of segregation:
As per this law, the alleles of a gene present on homologous chromosomes seperate at the time of gamete formation. The gamete recieves a single copy of allele because the homologous chromosomes seperate at time of gametogenesis.
Implications:
Answer 2 Given: Dominant allele H, Recessive allele h, hairy leaves are dominant to smooth
a) Genotype of smooth leaves: hh
b) Genotype of hairy leaves: Hh (heterozygous hairy), HH (homozygous hairy)
c) Genotypes of gametes produced by smooth leaved plant: h
d) Genotypes of gametes produced by hairy leaved plant: H, h
Answer 3 Let the two genes are A and B, where A is dominant over a and B is dominant to b
Genotype of heterozygous parents = AaBb
gametes formed : AB, Ab, aB, ab
Genotypic Ratio is 1:1:1:1
Answer 4 If the students have removed some of the corn kernels from genetic corn ears, the effect on result will depend on whether the removal is random or selective. If it is random (both type of kernels are removed), the results will not be effected much. If it is selective (a particular type of kernel was removed), then results will be highly effected and the mendel's laws may not hold good and those kernels should not be used for experiment.
Answer 5 Let the dominant allele is A and recessive one is a
a)Genotype of heterozygous parents = Aa
Genotype of gametes = A and a
The offsprings are as in punnet square
AA
(Phenotype: Dominant trait)
Aa
(Phenotype: Dominant trait)
Aa
(Phenotype: Dominant trait)
aa
(Phenotype: Recessive trait)
Phenotypic ratio is 3(Dominant trait): 1 (recessive trait)
Example: Similar results are in Mendel's cross of Height of garden pea plant
b) Let the two traits are represented by A and B respectively, where for first trait: A is dominant to a
second trait: B is dominant to b
Genotype of heterozygous parents: AaBb
Genotype of gametes: AB, Ab, aB, ab
The offsprings are as in punnet square:
AABB
(Phenotype: Both dominant traits)
AABb
(Phenotype: Both dominant traits)
AaBB
(Phenotype: Both dominant traits)
AaBb
(Phenotype: Both dominant traits)
AABb
(Phenotype: Both dominant traits)
AAbb
(Phenotype: Dominant A trait recessive B trait)
AaBb
(Phenotype: Both dominant traits)
Aabb
(Phenotype: Dominant A trait recessive B trait)
AaBB
(Phenotype: Both dominant traits)
AaBb
(Phenotype: Both dominant traits)
aaBB
(Phenotype: Recessive A trait dominant B trait)
aaBb
(Phenotype: Recessive A trait dominant B trait)
AaBb
(Phenotype: Both dominant traits)
Aabb
(Phenotype: Dominant A trait recessive B trait)
aaBb
(Phenotype: Recessive A trait dominant B trait)
aabb
(Phenotype: Both recessive traits)
Phenotypic ratio = 9 (Both dominant traits): 3 (Dominant A and recessive B trait) : 3 (Dominant B and recessive A trait) : 1 (Both recessive traits)
Example: Similar results are in Mendel's cross of Seed shape and seed colour in garden pea
Gametes A a AAA
(Phenotype: Dominant trait)
Aa
(Phenotype: Dominant trait)
aAa
(Phenotype: Dominant trait)
aa
(Phenotype: Recessive trait)