Florida International University Genetics Inheritance Questions

Answer ALL six (6) questions and post the answers in a single post:

1. A) Apply the concept of sex linkage to explain why color blindness is more prevalent in men than in women. B) Mary is concerned that she may be a carrier for hemophilia, a sex-linked condition located on the X chromosome. Mary is married to John, who doesn’t have hemophilia. Assuming Mary is a carrier, what are the genotype ratios expected for Mary and John’s kids (specify for boys and for girls)? C) Mary and John have 2 boys, none of them has hemophilia. Can we use this fact as proof that Mary does not carry the allele for hemophilia? Explain your argument.
2. In mammals, males have XY chromosomes and females have XX. The Y chromosome is usually small, with very few genes. While the X chromosome is large and has genes unrelated to sex characteristics, thus, females could potentially have twice as much gene product as males. A) How do cells compensate having two X chromosomes in females vs only one in males? B) If you clone a Calico cat or a tortoiseshell cat, would the clones have the same color pattern? Explain your answer.
3. In plants, long pollen grain is dominant to short grain and purple flower color is dominant to white color. You are mating two plants. One is homozygous recessive for both traits, flower color and pollen grain (llpp). The other plant is heterozygous for both traits (LlPp). A) What types of gametes do you expect each of these plants to produce (list the genotype of gametes each parent produces, not their offspring). B) What ratio do you expect for each allele combination in the gametes of these plants?
4. Continuing the example above of mating two plants, a homozygous recessive for pollen grain and flower color and the other heterozygous for both traits. A) What are the genotype and phenotype ratios you expect for the offspring? B) Which Mendelian assumption are you making when estimating those allele ratios?
5. After mating the two plants indicated in the example above, you find that 40% of the offspring have short pollen grain and purple flowers, 40% have long pollen grain and white flowers, 10% have short pollen and white flowers and the remaining 10% have long pollen and purple flowers. A) Are the genes for flower color and pollen grain assorting independently? B) What could you say about their location on the chromosome?
6. For the heterozygous parent plant in the example above: A) Draw the pair of homologous chromosomes showing the relative location of the genes for pollen grain and flower color. B) Which combination of alleles did the heterozygous parent inherit from each of its parents (the offspring’s grandparents)? C) Explain how you figured this out.