BIOL 103 Home

Biomorph Challenge #2

Biomorph 2. Population Genetics
Type, print out, and turn in BEFORE class.
10 points off for late work.
10 points off for lack of staple.

1. The Chief Spin Officer was fired because you blew away their first claim.
A message from the new Chief Spin Officer of the Biomorph mothership:

"Our advanced Biomorph genomes contain a special allele for Interspecies Cooperation, which is dominant to the recessive allele. Since the Interspecies Cooperation allele is dominant, its frequency will increase in our population, and any problems we have getting along with you will soon disappear."

What do you say?

2. In Galapagos, Akiko had especially hairy skin, a condition called hypertrichosis. Different types of hypertrichosis are caused by mutations in different genes, as described in OMIM. Based on Akiko's description in the book, and on information you find in OMIM, which genetic trait do you think she might have had and why? (Various answers possible.)

3. The von Kleist family shows frequent appearance of Huntington's disease, a dominant trait.

a. From the information you can find in the text of Galapagos, draw the family tree of the captain von Kleist and his brother. Define and include an appropriate genotype designation for each person.

b. Consider a hypothetical sister of Adolf and Sigfried. What are the possible genotypes for her and what chance does she have of having the disease?

c. You are a genetic counselor, and you are visited by a young person whose father died of Huntington’s disease who was planning to marry someone who did not have the disease in her family. What would you advise them and why? A DNA test now exists to detect whether one carries the Huntington allele. How would this change your advice?

4. In a certain community, suppose one in 500 people carries the gene for Huntington’s disease (one or both allele).

a. Use the Hardy-Weinberg Law to determine the allele frequency (p) for the Huntington allele.

b. If you carry one copy of the Huntington allele (p), does that also mean you will develop the disease and die?

5. Researchers have identified an allele of a gene that confers resistance to HIV virus, the cause of AIDS. The allele is a version of the CCR5 gene that has part of its sequence deleted (allele CCR5-delta 32). THe gene makes a cell surface protein that HIV needs to infect a cell.

The CCR5-delta 32 allele is present at a frequency of 0.08 in some European populations. Persons who are homozygous recessive (aa) show virtually complete resistance to HIV, and those who are heterozygous (Aa) have 78% lower risk of HIV infection. Those who are homozygous dominant (AA) have no resistance to HIV.

Find the percentages of the population that are:
--Carriers (Aa) and thus partly protected from AIDS.
--Homozygous (aa) thus completely resistant to AIDS.
--Normal (AA) thus completely susceptible to AIDS.

6. Explain how each of the following traits is determined by genes and/or environment:

* Hearing vs. Deafness
* Diabetes
* Spoken language

7. Vonnegut offers several hypotheses to explain how tortoises traveled to Galapagos.

a. Explain evidence supporting and evidence refuting each hypothesis.

b. Which hypotheses can neither be refuted nor proved? Why not?

8. Suppose a human evolved the ability to absorb solar energy through photosynthesis, instead of eating food.

a. What would we call the kind of evolution that generates a "plantoid" person? Would the person be able to interbreed with plants?

b. How many photons would the plantoid need to absorb in order to gain as much energy as you would from eating one cup of cornflakes? (449 kilo-Joules, kJ)