Human Genetics and Medicine - BIOL 272    EXAM II - redo Part I                     NAME:

Part I: [46 points] Variable units.  Answer all the questions.

1.  Fill in the table for each of the following human genes.  The letters for the gene’s name is given in all uppercase; you must decide what should really be upper and lower case in the symbol. [24 points]

trait which is passed on as ...	achondroplasia (ACH) - dominant (a type of dwarfism)	Gaucher disease (GD) recessive (a lysosomal storage disorder)
wild type allele
mutant allele
dominant allele
recessive allele
“normal” genotypes
“abnormal” genotypes
show mating
heterozygote x normal
offspring genotype (s)
offspring phenotype (s)
show mating
heterozygote x abnormal
offspring genotype (s)
offspring phenotype (s)

 
2.  Solve the following pedigree. For each individual, write the genotype [write it next to the symbol in the pedigree]. Is the inheritance pattern for the indicated trait recessive, dominant, other? Explain.  [11 points]

Name the propositus (proband):                                                                                _______________ Inheritance pattern:   _______________ (explain) What phenotypic ratio would one expect among the offspring if II-2 and II-6 had children?  Is this mating legal in the USA (assuming these are people)?  _______________ What phenotypic ratio would one expect among the offspring if III-2 and II-6 had children?  Is this mating legal in the USA (assuming these are people)?  _______________ At the right of the pedigree, indicate what Mendel would have called each generation.

3.  While you are working as a genetic counselor, a couple asks you for advice.  They have had one child who died of Tay Sachs, a lethal recessive disorder.  They hope to have more children, and want to know: [11 points]

    a. What is the chance that their next child will have Tay Sachs?


    b.  If their next child is healthy, what is the chance that the third child will be healthy as well?



    c. What is the chance of their having four normal children, in their next four attempts?



    d. What is the chance of their having four normal girls, in their next four attempts?


        e.  If there is a prenatal test for Tay Sachs, why might this couple chose to have such a test done with subsequent pregnancies?  That is, for what purpose would such a test be done?








4.  Fill in the following table.  Show your work for possible partial credit; if you choose to do this, be sure that your work is legible and labeled sufficiently clearly to be understood by someone other than yourself.  Be sure to list the genotypes & phenotypes in a sensible order in the first column, and then to use the table as a table. [10 pts] (note - an extra column has been added for re-do)

          

	AaBb x AaBb	AB/ab x Ab/aB	Ab/aB  x Ab/aB	AB/ab x AB/ab
genotypes
phenotypes