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X-Linked Traits

1. Eye color is an X-linked gene and red is dominant to white in Drosophila. If I mate a red eyed male with a white eyed female and I mate a white eyed male with a pure breeding red eyed female, the progeny from both crosses will be the same.

A. True
B. False

2. Mary met her partner Bobby at a support group for families dealing with color blindness. Mary and Bobby are unaffected but both have one brother who is affected. They have no knowledge of other family member. Which of the following is true?

A. There is a 100% probability that they will have an affected child.
B. They might both be heterozygotes.
C. Since neither one of them is affected, they are not at risk of having an affected child.
D. Bobby will not pass a mutant allele to either sons or daughters.

Solution Preview

Genetics Multiple Choice/True & False
1. Eye color is an X-linked gene and red is dominant to white in Drosophila. If I mate a red eyed male with a white eyed female and I mate a white eyed male with a pure breeding red eyed female, the progeny from both crosses will be the same.

If eye color is an X-linked gene, which mean the trait red is on the X-chromosome. X-linked traits are typical because it only need one recessive allele present for the phenotype to be expressed in the male. (1) Some examples are color blindness. Most men are colorblind because of the X-linked color blind gene that they carried on their X- chromosome.(1)

Let R= red ...

Solution Summary

What is X-linked traits? X-linked traits are genetic traits determined by genes located on the X-chromosomes. Genes are regions of DNA found on chromosomes that carry information for protein production and are responsible for inheritance of specific traits. There are two alleles per gene. One allele for a trait from a gene is inherited from each parent. Sex linked or X-linked traits are passed from parents to offsprings through sexual reproduction.

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