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Drosophila has a diploid chromosome number of 2n = 8, which includes one pair of sex chromosomes (XX in females and XY in males) and three pairs of autosomes. Consider a Drosophila male that has a copy of the A1 allele on its X chromosome (the Y chromosome is the homolog) and is heterozygous for alleles B1 and B2, C1 and C2, and D1 and D2 of genes that are each on a different autosomal pair. In the diagrams requested below, indicate the alleles carried on each chromosome and sister chromatid. Assume that no crossover occurs between homologous chromosomes.
a. What is the genotype of cells produced by mitotic division in this male?
b. Diagram any correct alignment of chromosomes at mitotic metaphase.
c. Diagram any correct alignment of chromosomes at metaphase I of meiosis.
d. For the metaphase I alignment shown in (c), what gamete genotypes are produced at the end of meiosis?
e. How many different metaphase I chromosome alignments are possible in this male? How many genetically different gametes can this male produce? Explain your reasoning for each answer.
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