BIO 301, Genetics - Spring 2000

Review 1 - Mendelian Genetics, DNA Replication, Transcription


Provide thorough, but concise, answers to 8 of the 9 following questions.
There is no time limit to this test, but it should not take you more than 2 hours to complete.
The review is closed book.
Calculators are permitted.
All questions are worth 20 points.
If your handwriting is lousy, please type your answers.
Staple all pages together and do not put your name on any page other than this cover page.
Return completed review to me no later than 10:30am, Wednesday, February 23, 2000.

Name (please print):

Pledge and signature:


Answer 8 of the 9 questions


1. Two features of eukaryotic genomes make their replication more difficult than the replication of prokaryotic genomes. What are these two features and what mechanisms exist to circumvent these potential problems?


2. A true-breeding purple-eyed, spotted frog is mated with a true-breeding green-eyed, spotless frog. All the F1 frogs are blue-eyed and have spots. The F1 frogs are mated and the F2 generation yields the following phenotypic ratio:

27/64 blue-eyed, spotted

12/64 green-eyed, spotted

9/64 blue-eyed, spotless

9/64 purple-eyed, spotted

4/64 green-eyed, spotless

3/64 purple-eyed, spotless

Explain how eye color and spots are inherited in these frogs. Provide genotypes for all frogs (parents, F1s, and F2s).


3. It is known that tryptophan, kynurenine, 3-hydroxyanthranilic acid, and indole are precursors in the niacin biosynthetic pathway of the fungus Neurospora. Describe an experiment that would allow you to determine the correct order of precursors in this pathway.


4. Two genes, gene A and gene B, are on the same chromosome, 20 map units apart. The following cross is conducted: aaBB x AAbb. The resulting F1s are self-crossed. If 1000 F2 offspring are then analyzed, what phenotypes would you expect to observe and how many of each phenotype should you observe?


5. In the following cross, RrTt x rrtt, four phenotypes of offspring are observed in the following numbers:

R T : 1000

R t : 880

r t : 1020

r t : 900

Based on these results, would you conclude that these genes linked or unlinked? Explain.


6. Davidson Wildcats can have black, red, gray, or albino fur. Individual animals (not necessarily true breeding) showing these colors were mated and the phenotypes of the offspring were tabulated. From these data, determine the inheritance of fur color in Davidson Wildcats. Show the genotypes for all parents and progeny.

A - albino B - black R - red G - gray

Progeny Phenotypes

Cross Parents B R G A
1 B x B 22 0 0 7
2 B x A 10 9 0 0
3 G x G 0 0 34 11
4 R x G 0 24 11 12
5 B x A 13 0 13 0
6 B x G 19 20 0 0
7 B x R 18 20 0 0
8 B x R 14 8 6 0
9 R x R 0 26 9 0
10 G x A 0 0 15 17


7. How does meiosis differ from mitosis?


8. Explain what we mean when we say that the DNA strands in double stranded DNA are antiparallel? Briefly explain how this antiparallel orientation affects DNA replication.


9. For the following pedigree, supply genotypes for as many individuals as possible. Also, what is the probability that individuals 7 and 8 will have a girl with the disease? What is the probability that the next child of couple 5/6 will be either a girl without the disease or a boy with the disease?