Application Activity 2.  Questions

Application Activity 3.  Colorblind -- are you?

Pedigree Activities:

Harold works in a fish market, but the odor does not bother him because he has anosmia, an X-linked recessive lack of sense of smell.  Harold's wife, Shirley, has a normal sense of smell.  Harold's sister, Maude, also has a normal sense of smell, as does her husband, Phil, and daughter, Marsha, but their identical twin boys, Alvin and Simon, cannot detect odors.  Harold and Maude's parents, Edgar and Florence, can smell normally.  Draw a pedigree for this family, indicating people who must be carriers of the anosmia gene.

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Questions:

1.  How is sex expressed at the chromosomal, gonadal, phenotypic, and gender identity levels?

2.  How do genes in the pseudoatuosomal region of the Y chromosome differ from X-& Y homologs?

3.  What are the phenotypes of the following individuals?
    a.  a person with a mutation in the SRY gene, rendering it nonfunctional
    b.  a normal XX individual
    c. an XY individual with a block in testosterone synthesis

4.  List the cell types and hormones that participate in development of male reproductive structures.

5.  List the events that must take place for a fetus to develop as a female.

6.  Cite evidence that may point to a hereditary component to homosexuality.

7.  Why would it be extremely unlikely to see a woman who is homozygous dominant for an X-linked dominant disease?

8.  Why are male calico cats very rare?

9.  How might X inactivation cause patchy hairiness on women who have congenital generalized hypertrichosis (CGH), even though the disease-causing allele is dominant?

10.  How does X inactivation even out the "dose" of X-linked genes between the sexes?

11.  Traits that appear more frequently in one sex than the other may be caused by genes that are inherited in an X-linked, sex-limited, or sex-influenced fashion.  How might you distinguish among these possibilities?

12.  Cite evidence that genetic contributions from both parents are necessary for normal prenatal development.

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Colorblind:  Are you?

Go to:
http://members.aol.com/nocolorvsn/color.htm
Test yourself for colorblindness.  Are you colorblind?  If so in what areas?  What are the genetics of colorblindness?

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