2. We could describe the ploidy of a certain organism as 3N.

a) What is 3 in this case?

b) What is n (define it)

c) What is the ploidy of a human?

d) What is the n value for a human?

e) How many autosomes does a human have?

3. Describe with a labelled sketch the structure of an eukaryotic chromosome in:

A) mitotic prophase (show and label: chromatid, centromere)

B) interphase (show and label: histones, nucleosomes, DNA)

C) metaphase of meiosis I with cross over (show and label: Sister chromatids, chiasma, centromere)

4. Draw out the stages of meiosis for a cell where 2N=6. How many different gametes can be formed? How many different gametes can result if there is only one crossover among all the chromosomes? If a cross over occurs between each of two homologues?

5. A mule is the product of the mating between a horse and a donkey. Mitosis is fine in the mule but meiosis is abnormal. Why is this so?

6. Organisms with different genotypes can have the same phenotype!!

Is this statement true or false? Explain why.

7. The gene specifying blood group determinants can occur in three alleles A, B, and O. A and B are co-dominant, while O is the recessive allele. If Luke Skywalker's mother was blood type A and Luke himself were type B, what blood type(s)-if any-would Darth Vader have to be for us to unequivocally rule him out as Luke's natural father?

8. The crossing over frequency between genes A and B is 7 percent: between B and C, 17 percent; between A and C, 10 percent; between C and D, 1 percent; and between B and D, 18 percent. What is the frequency of crossing over between A and D?

9. Cystic fibrosis is inherited as a simple autosomal recessive in humans. If a woman who is a carrier marries a man who is normal and not carrying the trait, what percent of their children would be expected to have the disease?

10. Brown eye color is dominant in humans; blue is recessive. If a brown-eyed man marries a blue-eyed woman and they have a brown-eyed boy and a blue-eyed girl, we can safely conclude that

a) the man is not the true father of one of the children

b) the man is heterozygous

c) eye color is sex-linked

d) both parents are homozygous

11. Brown eyes (B) are dominant to blue eyes (b). A blue-eyed man, both of whose parents had brown eyes, married a brown-eyed woman whose father was blue-eyed and whose mother was brown-eyed. This man and woman have a blue-eyed child. What are the genotypes of all the individuals mentioned?

12. The haploid green alga Chlamydomonas can normally utilize the organic molecule acetate as a carbon source for growth. A mutant was found that could not utilize acetate and also required tryptophan. The double mutant, a t, was crossed with a normal, A T, and the resultant progeny were as follows:

AT 48

at 52

At 49

aT 51

Do these genes appear linked or unlinked? How do you know?

Another mutant (b) was obtained that required biotin for growth. When the double mutant ab was crossed to the wildtype Chlamydomonas (AB), the following progeny types were obtained:

AB 129

Ab 13

ab 141

aB 17

Are these genes linked or unlinked? How many map units apart are they?

13. The Organic Chemistry Lab nerd thinks he has developed a new anti-cancer drug. He tells you that it will specifically cause a high rate of nondisjunction during Anaphase II, and he wants you to feed it to cancerous rats to see if it suppresses the growth of their cancer cells. Explain why you think this new drug will or will not be effective.

14. Indicate at what stage of meiosis each of the following is initiated; If it is not a part of meiosis, state so.

1) Homologous Chromosome Pairing

2) Crossing Over

3) Separation of Sister Chromatids (assume no crossing over)

4) Separation of Nonsister Chromatids (assume no crossing over)

5) Synapsis

6) Chromosome Condensation (folding)

7) Centriolar Movement

8) Independent Assortment

9) Chromosome Replication 10) Reformation of Nuclear Envelope