You'll notice that some questions look familiar... I used some for your homework. :)

1. In your studies of sex chromosome anomalies you identify a male who is a XYY/XY mosaic. What is one specific way this mosaic male could have been generated? Please explain in genetic terms.

2. Could genetic testing for carrier status ever be 100% accurate? Why or why not?

3. A “zoo” blot was performed using a piece of DNA derived from a human chromosome jump while searching for a gene involved in hereditary colon cancer. The results are shown below. Does this DNA warrant additional analysis? Please explain briefly.

5. a. Which modes of inheritance are consistent with the following pedigree? b. Which mode of inheritance is most likely?

b. Starting with one homologous chromosome pair, diagram the products of nondisjunction in meiosis II, chromosome loss in meiosis I, and normal meiosis beginning with a normal spermatogonium (pre-meiotic cell) in each case.

c. Draw squares around the sperm that would produce a normal fetus when combined with a normal egg.

7. Let's consider a maternally imprinted (paternally expressed) gene. You received allele A from your mother and allele B from your father. You pass the A allele to both of your two children, a boy and a girl. Your spouse has two C alleles.

a. Diagram the chromosomes and indicate 1) which allele the chromosome is carrying, 2) whether the allele is active, and 3) from where the individual received each chromosome.

8. Assume that the frequency of the recessive Rh negative allele, r, in a particular city is 0.1. Please show your work.

b. What genotypic frequencies, RR, Rr, and rr, are predicted by the Hardy-Weinberg law?

c. There are forty children in one of the city's kindergartens. How many of these children would be expected to show the dominant phenotype?

9. A man with 46 chromosomes (46, XY) appears completely normal. He and his wife have been unable to have any children. His wife has experienced four miscarriages. In searching for the cause of this problem, a cytogeneticist finds that he has a translocation between chromosome 15 and chromosome 4.

a. What is the reason for the miscarriages? Please be specific about the man's problem and how it affects his children.

b. Describe the two karyotype(s) would you expect to see in the miscarried embryos?

c. Would it be possible for this man to have any phenotypically normal children, assuming his wife has a normal karyotype?

10. Analyzing LOD scores allows geneticists to map human genes by combining data from many small human families into one large family. The first step is to identify recombinants and then calculate LOD scores. You are collecting data to map the hypothetical dyslexia gene that is inherited as autosomal dominant with respect to the STS locus D903. The D903 alleles are noted below each symbol (a, b, c, or d).

b. Please explain how you determined which offspring are recombinant and which are not.

c. The following is a table of LOD scores. Which locus is closest to your gene of interest? Please explain.