Question

4. You have a Drosophila that has the following genotype: RrKKcc List all of the possible gametes that could be produced by this fly. (Hint: each gene must be represented in the gamete!)

5. (a) Describe what is meant by a carrier. (b) Provide an example of a genetic disorder that can produce carriers. (c) Do dominant genetic disorders produce carriers? Why or why not?

Answer 1

Ans4: The genotype of Drosophila- RrKKcc

Gametogenesis is a type of meiosis cell divison, hence each gamete will get only one copy of chromosome. Due to this the hetrozygous gene will produce two different type of gametes and Homozygous gene will produce only one type of gametes for above genotype RrKKcc, Rr is heterozygous and KKcc is homozygous. Hence only two combiation of gametes will arise and that will be:

The possible gamates will be - RKc, rKc

Ans5 a) Carrier means that the person is having defective allele but due to recessive in nature, the dominant allele able to perform function in heterozygous condition. The genotype of carrier individual will be heterozygous. We can also understand by study the inheritance of cystic fibrosis. It is autosomal recessive disorder,

so affected person genotype will be AcAc

so unaffected person genotype will be ACAC

and carrier person genotype will be ACAc

Dominant genetic disorder is a genetic disorder where single mutant allele is capable to express disease phenotype. Hence dominant genetic disorder will never have carrier individuals.