Biology Forums - Study Force

10. In Drosophila melanogaster the sex-linked recessive allele singed (sn, at map position x=21) causes the bristles to look twisted and bent, as if burnt in the homozygous or hemizygous condition (sn/sn or sn/y). The sex-linked recessive mutation vermillion (v, at map position 33) produces a bright orange/red color. Vermillion eyed flies are easily distinguished from the dull red eyed wild-type files. Wild-type virgin female flies are mated to singed, vermillion males. This produces an F1 that is phenotypically wild-type. This F1 is allowed to mate.
a.Show the genotypes of both the male and female F1 progeny.
b.Show the gamete types and their relatives expected proportion of the F1 female.

11. Infantile amaurotic idiocy (Tay Sachs disease) is a recessive hereditary abnormality causing death within the first few years of life only when homozygous (ii). The dominant condition at this locus produces a normal phenotype (I-). Abnormally shortened fingers (brachyphalangy) are thought to be due to a genotype heterozygous for a lethal gene (BBL), the homozygote (BB) being normal, and the other homozygote (BLBL) being lethal. What are the phenotypic expectations among teenage children from parents who are both brachyphalangic and heterozygous form infantile amaurotic idiocy?
c.Show the genotypes of both the male and female F1 progeny.
d.Show the gamete types and their relatives expected proportion of the F1 female.

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Thanks so much!