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.


Diagram any correct alignment of chromosomes at metaphase I of meiosis.

A wild-type Drosophila male and female are crossed, producing 324 female progeny and 161 male progeny. All their progeny are wild type.

Design an experiment that will test your hypothesis, using the wild-type progeny identified above. Describe the results you expect if your hypothesis is true.

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.

What is the genotype of cells produced by mitotic division in this male?

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.

Diagram any correct alignment of chromosomes at mitotic metaphase.

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.

For the metaphase I alignment shown in (c), what gamete genotypes are produced at the end of meiosis?

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.

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.

The cell cycle operates in the same way in all eukaryotes, from single-celled yeast to humans, and all share numerous genes whose functions are essential for the normal progression of the cycle. Discuss why you think this is the case.