Human Heredity: Principles and Issues (MindTap Course List)
11th Edition
ISBN: 9781305251052
Author: Michael Cummings
Publisher: Cengage Learning
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A Drosophila embryo dies during early embryogenesis due to a
recessive maternal effect allele called bicoid−. The wild-type allele
is designated bicoid+. What are the genotypes and
the embryo’s mother and maternal grandparents?
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- In Drosophila, a cross (cross 1) was made between twomutant flies, one homozygous for the recessive mutationbent wing (b) and the other homozygous for the recessivemutation eyeless (e). The mutations e and b are alleles oftwo different genes that are known to be very closelylinked on the tiny autosomal chromosome 4. All the progeny had a wild-type phenotype. One of the female progeny was crossed with a male of genotype b e/b e ; we willcall this cross 2. Most of the progeny of cross 2 were of theexpected types, but there was also one rare female ofwild-type phenotype.a. Explain what the common progeny are expected tobe from cross 2.b. Could the rare wild-type female have arisen by (1)crossing over or (2) nondisjunction? Explain.arrow_forwardA maternal effect gene in Drosophila, called torso, occurs as a functionalallele (torso+) and a nonfunctional, recessive allele (torso−)that prevents the correct development of anterior- and posterior-moststructures. A wild-type male (torso+torso+) is crossed to a female ofunknown genotype. This cross produces offspring (larva) that are allmissing their anterior- and posterior-most structures and therefore die during early development. What are the genotype and the phenotypeof the female fly in this cross? What are the genotypes andphenotypes of the female fly’s parents?arrow_forwardIn Drosophila, gray body color is dominant over ebony body color,while long wings are dominant over vestigial wings. Work thefollowing crosses through the F2 generation, and determine thegenotypic and phenotypic ratios for each generation. Assumethat the P1 individuals are homozygous: (a) gray, long * ebony,vestigial, and (b) gray, vestigial * ebony, long, and (c) gray,long * gray, vestigial.arrow_forward
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