I. Allelic and Genic Interactions

II. Sex Determination

III. Linkage:

1) Consider the results from test cross: AaBb x aabb:

- assume complete dominance for each locus.

AB = 23

Ab = 9

aB = 6

ab = 18

Conduct a Chi-Square test of independence to determine whether the genes are linked or are assorting independently. Use the p = 0.05 level of significance to evaluate the null hypothesis, with the associated critical Chi-Square value (from the table) of 3.84. If the genes are linked, show the arrangement of alleles on the chromosomes in the AaBb parent, and show the distance between the loci.

2) Consider these results from a testcross: DdEe x ddee

- assume complete dominance for each locus

DE = 14

De = 22

dE = 28

de = 10

Conduct a Chi-Square test of independence to determine whether the genes are linked or are assorting independently. Use the p = 0.05 level of significance to evaluate the null hypothesis, with the associated critical Chi-Square value (from the table) of 3.84. If the genes are linked, show the arrangement of alleles on the chromosomes in the AaBb parent, and show the distance between the loci.

3) Consider these results from a testcross: FfGg x ffgg

- assume complete dominance for each locus

FG = 45

Fg = 43

fG = 12

fg = 10

Conduct a Chi-Square test of independence to determine whether the genes are linked or are assorting independently. Use the p = 0.05 level of significance to evaluate the null hypothesis, with the associated critical Chi-Square value (from the table) of 3.84. If the genes are linked, show the arrangement of alleles on the chromosomes in the AaBb parent, and show the distance between the loci. If they are assorting independently, think of ANOTH REASON why the results deviant from a typical 1:1:1:1 ratio. Examine the ratios of each locus by itself. Anything screwy?

4) Consider these results from a testcross: AaBbDd x aabbdd

- assume complete dominance for each locus.

ABD = 24

ABd = 40

AbD = 75

Abd = 125

aBD = 132

aBd = 84

abD = 30

abd = 10

Suppose you know the loci are on the same chromosome as a consequence of previous research. Show the arrangement of alleles on the chromosomes in the AaBbDd parent, and show the distance between the loci.

5) What is the "Interference Coefficient" between these loci?

6) Give three pieces of evidence support the hypothesis that Archaeans and Eukaryotes are more closely related to one anaother than either is the Eubacteria.

7) Provide a quantitative extrapolation demonstrating the huge amount of genetic variation that can be produced in a baterial population in just a few hours, simply as a consequence of mutation and a rapid rate of reproduction.

8) Describe the pattern of growth you would expect from this bacterial strain (met-, leu-, bio+, lys+) on complete medium, minimal medium, and media supplemented with methionine and leucine.

9) Why do F+ strains cause recipients to transform into F+, but Hfr strains do not?

10) Given the results below, map the genes and location of Hfr insertions (origins) on the bacterial chromosome. The chemicals are the names of biologically important molecules that the receipient can synthesize ONLY AFTER the conjugation reaction has proceeded for the amount of time indicated.

Hfr 1: threonine (1 min.), biotin (5 min.), glycine (11 min.), isoleucine (14 min.)

Hfr 2: biotin (2 min.), threonine (6 min.), methionine (14 min.), isoleucine (19 min.)

Hfr 3: glycine (3 min.), isoleucine (6 min.), methionine (11 min.), threonine (19 min.)

12) What is an F' plasmid, and why do recipients both receive chromosomal genes (like Hfr) while ALSO become F' themselves (like F+)?

13) What is bacterial transformation, under what conditions does it occur, and why is this response adaptive under these conditions?

14) Using the diagram produced in class (and distributed separately), describe how a virus can transfer a gene from one bacterium to another.

15) Restriction enzymes cut DNA at specific nitrogenous base sequences. When plasmid DNA and a region of human DNA are cut by the same restriction enzyme, why can they combine?

16) Once a gen is in a plasmid, how can you get it into a bacterium?

17) Using ampicillin-resistant plasmids and selective media with ampicillin present, describe how you can distinguish cells that have accepted a plasmid from those that have not.

18) Using a ss-DNA probe (that is either radiacively labelled or tagged with a flourescent marker), explain how you can isolate colonies that have not only accepted a plasmid (described above), but have a human gene on that plasmid.