Three point mapping assignment in lieu of class 10/9/08

This exercise is designed to help you understand three point mapping problems, and to give you more opportunities to practice solving them. Please follow the instructions carefully.

Read through ALL of the instructions before beginning the project.

You will be constructing two problems based on the same map, and posting them to the Blackboard Discussion Board threads set up here. Then, on or after Tuesday, 10/14/08, you will post the solution map to a separate solutions thread.

1. Choose names for three genes (I recommend something fun like cutsie, tootsie, whoopsie, but you can be dull if you prefer) with mutant/wild type & dominant/recessive clearly indicated in their designations.

2. The map shall be established as follows:
        a. arrange the three genes on the chromosome, so that all are linked; two should be coupled and the other in repulsion to them both (in any order).
        b. the distance between the first two genes is the sum of the digits of your age. For example, if you are 24 the distance is 6 mU.
        c. the distance between the middle & third genes is the difference between the digits of your age, * 4. So, if you are 24, the distance is (4-2)*4 = 2*4 = 8.
        **   if the difference between the digits is 0, use the sum of the last two digits of your street address or phone number.
        d. If the two distances calculated in (b) & (c) are the same, choose an alternative distance for one of them (using your street address or phone number) : this should be a number between 5 & 20.

3. Generate data representing two testcrosses of an organism containing a chromosome with this genetic map. You may also write a story to go along with it, if you choose. Generate at least 1000 progeny. The two sets of data represent the situation if

        a. there is NO INTERFERENCE i.e. the frequency of DCO recombinants is as expected.

        b. 0 < I < 1. There is interference, but there are at least some DCO recombinants.  I = smaller digit in your age/larger digit in your age (so, if you are 24 = 2/4 = .5 If you are a double digit, subtract one year (make yourself younger) and then calculate.

Publish the two sets of data as a reply posting to this discussion. Do NOT indicate which problem (a or b) is which. Flip a coin: if it comes up heads list (a) before (b). If it comes up tails, list (b) before (a). Thus, we would expect that about half the postings will have I = 0 posted first, and about half to have I = 0 posted second.

It is best if you scramble the order of the progeny phenotypes.

The subject line should be something recognizable, perhaps related to the story you might have written.

4. On or after Tuesday, 10/14/08 post your map solution, and the value of I for case (b) in the following discussion thread set aside for that purpose - NOT IN THE FIRST ONE. The subject line should match the one you used for the original problems' post.

SOLUTIONS ARE MAPS SHOWING BOTH PARENTS' GENOTYPES AND PHENOTYPES, MAP DISTANCES, AND INTERFERENCE VALUE.

5. Solve at least 6, and preferably all your classmates' problems for practice.

6. Check back later to see if your solutions are correct. Do not "cheat" and look at the solutions before solving the problems!