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NOTE: you may submit this assignment via e-mail (bkbaxter@lclark) if you prefer. I will reply to you as soon as I receive it. If the deadline is approaching and you have not received a reply, please assume that I did not receive it, and make other arrangements to get it to me on time!

a. They may appear as if they were homozygous for the wild-type allele

b. They may appear mutant

c. They breed true

d. They may have altered enzyme activity

2. (1 pt) Causes of heritable mutation include all of the following except

a. radiation

b. chemicals

c. errors in DNA replication

d. errors in copying DNA into mRNA

3. (1 pt) Crossing over (recombination) occurs during (circle all that apply)

a. metaphase of meiosis I

b. metaphase of mitosis

c. prophase of meiosis II

d. metaphase of meiosis II

 

4. (3 pts) You are studying a bacterium that has the remarkable property of being able to survive exposure to high levels of radiation. Although the general phenomenon has been characterized and described, the genetics underlying this ability have not yet been elucidated. Describe how you would design and carry out a genetic screen to do just that. You may make the following assumptions:

• This bacterium has a small genome (roughly 4,000 kb), which is compact. Like other bacteria, this organism lacks introns.
• Existing transformation technologies (calcium chloride, electroporation) and plasmids will work for your organism.
• Other than radiation, standard methods of mutagenesis will work for your organism.
• This bacterium is haploid and grows clonally. It can be maintained on standard agar plates.

You should describe how you would isolate and characterize mutants, determine the order of the genetic loci (i.e. which gene product acts first, which acts next, and so on), and isolate individual genes.

5. (4 pts) You are studying a human neurological disorder which strikes children between the ages of 6 months and 3 years. Once it strikes, it is rapidly degenerative and invariably fatal. In studying inheritance patterns, you have learned that this illness is single-gene recessive, non-sex-linked, and strictly genetic. In other words, children who inherit two disease-bearing alleles at this locus inevitably get the disease, while heterozygotes are phenotypically normal. You have also discovered a small religious community in New York among whom this disease is extraordinarily prevalent. The members of this community are willing to collaborate with you in providing blood samples for testing and research.

Describe how you could use RFLP and/or PCR fingerprinting analysis to determine the chromosomal region associated with this illness. Then describe how you could identify the actual gene involved. You may assume that the human genome project has been completed, but that the gene for this illness has not been identified as such or functionally characterized.

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