I. Allelic, Genic, and Environmental Interactions

II. Sex Determination and Sex Linkage

1) What does the SRY gene actually make, and how does it influence sexual development?

2) How was the effect of this gene discovered?

3) What is "X-dosage compensation", and why does it occur? What is the Lyon hypothesis (book)?

4) How does X-inactivation cause mosaicism in females? Include reference to the differential effects that occur when the inactivation occurs at different times in development.

5) Describe one pattern where temperature influences sex determination. Now, provide two hypotheses regarding HOW this might occur at a cellular level, involving genes and proteins.

6) How can the size of an organism influence sex determination? Provide an adaptive explanation for this pattern.

7) How can the sizes/sex of other organisms in a population influence sex determination? Provide an adaptive explanation for this pattern.

8) Explain what causes colico and tortoiseshell coat color in female cats.

9) Consider this cross: X^BX^b x X^BY. If B exhibits complete dominance, what will be the phenotypic ratio in the offspring. Remember that the sex of the offspring is a part of the phenotype!

10) Humans have "Lygaeus" sex determination. Explain how chromosomal sex determination occurs in fowl and in fruit flies.

11) The environment determines sex in many species; describe an example invovling temperature and and example involving social hierarchy.