In Drosophila, a cross was made between a female heterozygous for the recessive genes ct (cut wings) and se (sepia-coloured eyes) and a sepia male. Among their female progeny, half the phenotypes were wild-type and half sepia. Among their male progeny were 1/4 wild-type, 1/4 cut, 1/4 sepia, and 1/4 cut and sepia. Is either of these genes sex-linked? What are the genotypes of the parents and their offspring?
See the later post for How to Search:
Sra
I don't know it
To determine if either of the genes is sex-linked and to find the genotypes of the parents and offspring, we need to analyze the given data.
Let's start by understanding the phenotypic ratios of the offspring:
Among the female progeny:
- Half the phenotypes were wild-type.
- Half the phenotypes were sepia.
Among the male progeny:
- 1/4 were wild-type.
- 1/4 were cut.
- 1/4 were sepia.
- 1/4 were both cut and sepia.
From these ratios, we observe that the proportions of wild-type, cut, and sepia phenotypes are equal in both male and female progeny. This indicates that neither of these genes is sex-linked. If they were sex-linked, we would typically observe different ratios depending on the sex.
Now, let's determine the genotypes of the parents and their offspring:
Female parent: Heterozygous for the recessive genes ct (cut wings) and se (sepia-coloured eyes).
We can represent this genotype as: ct/se
Male parent: Sepia (genotype is not given explicitly, so we'll represent it as: se/se)
Now, let's analyze the genotypes of the offspring based on the given phenotypes:
Female progeny:
- Half are wild-type: These would have the genotype: CT/SE
- Half are sepia: These could have either of the following genotypes: ct/se or ct/SE
Male progeny:
- 1/4 are wild-type: These would have the genotype: CT/SE
- 1/4 are cut: These would have the genotype: ct/SE
- 1/4 are sepia: These could have either of the following genotypes: ct/se or ct/SE
- 1/4 are both cut and sepia: These would have the genotype: ct/SE
To recap:
Female parent genotype: ct/se
Male parent genotype: se/se
Genotypes of the offspring:
Female progeny: CT/SE, ct/se or ct/SE
Male progeny: CT/SE, ct/SE, ct/se, or ct/SE
It's important to note that the genotypes of the offspring are deduced based on the observed phenotypes and the known genetic principles. To confirm the genotypes more accurately, further genetic analysis, such as breeding experiments or molecular techniques, may be required.