Problem Set #11 to Be Handed out Friday 11-10-2000
Problem Set 12, Fall 2018Name:
8 points total
1. A rare autosomal recessive disorder causes pink hair. A non-carrier male and an affected female marry. Consider the following pedigree and RFLP analysis prepared using HindIII, Southern blot, and a probe with a human sequence known to hybridize to sequences closely linked to the gene responsible for this disorder.
a. Diagram each of the different haplotypes (group of markers that tend to be transmitted together because of linkage) of I-1 and I-2 showing the restriction map and fragment lengths. Show all HindIII restriction sites on each map.
b. On the restriction map, indicate the area to which the radioactive probe must hybridize in order to detect the fragments seen by Southern analysis.
c. To which haplotypes (essentially pattern of each chromosome) does the mutant allele of the gene seem to be linked in this family.
d. Why does individual III-1 only show one band in the RFLP analysis?
e. Which individuals are probably carriers?
2. Your friend just got a new job in a research lab in Brazil studying tropical butterflies. She has recently isolated a new mutant butterfly that produces fluorescent blue wings. She calls the mutation flb. While attempting to establish a line of these butterflies for her lab, she crosses an flb female with a wild type male and all of the progeny have fluorescent wings. When she performs a reciprocal cross between a wild type female and an flb male the progeny are all wild type. Suggest three plausible explanation for these results. How would you distinguish between these possibilities?
3A. In general as we have seen this semester, reciprocal crosses produce the same results. However, we have encountered several exceptions to this general rule. Provide 4 examples where reciprocal crosses produce different results. Please include an example of such a cross and an explanation for the reason for the difference.
B. In your studies of the poison dart frog Y. abughofahae, you discover that there are two true breeding populations in the wild. The first population has bright red skin and the second has brilliant blue skin. You wish to understand the genetic basis of skin color in Y. abughofahae, so you cross frogs from population 1 with frogs from population 2 (i.e. red frogs X blue frogs). The F1 progeny all have purple skin. You cross purple F1’s to produce F2’s, and obtain the results shown below.
307 red frogs
298 blue frogs
883 purple frogs
92 white frogs
1580
i. What are the genotypes of the F2 frogs?
ii. If you cross red F2 frogs X white F2 frogs, what is the probability of getting white offspring?
4. In your travels through the tropics you isolate a strain of poison dart frogs that has the following unusual features. Every generation you are able to identify a high frequency of mutations. Unfortunately, these mutations are not stable and often revert in the next generation (even thought kept under identical conditions) making them difficult to map genetically. Provide a plausible molecular explanation for the high frequency of reversion seen in this population.
5. You are studying a rare mutant phenotype and perform PCR to analyze the suspected gene that is associated with the phenotype. You notice that the allele found in mutants is much longer than the wild type allele. You also notice a high frequency of reversion among mutants.
a. What caused the mutant allele?
b. What are two mechanisms by which it could have moved into the gene (depending upon what type of transposable element it is)?
6. You wish to study development, the process by which an embryo develops to produce a mature animal. Which organism would you choose? Justify your answer.
7. You study a rare, but evolutionarily interesting species of tunicate. You want to write a grant in which you propose to sequence this animal’s genome. Please describe the general approach that you will use to sequence the genome. Assume that the genome contains many repetitive DNA sequences.
8. Reggaephilia, which causes a great fondness for Reggae music, is inherited as an autosomal dominant. Below is the pedigree analysis of reggaephilia in a single family. You perform a Southern blot analysis of DNA from family members, using a probe that recognizes a specific polymorphism.
a. Based on the blot shown above, are any of the polymorphisms likely to be linked to reggaephilia? If so, which one(s)? Numbers on the left show the sizes in kilobase pairs of bands detected.
b. Draw a map showing the bands in the original parents. Please indicate the approximate location of the nucleic acid probe that was used to detect the bands that were seen on the blot.
c. How would linked polymorphisms help you to clone the gene?
1