The Final exam will be similar to this but with all multiple choice etc. No writing. Also less emphasis on chapter 20. And no tetrad analysis.

 

1. Define 10 of the following 16 terms (3 pts each = 30 pts): allele, wild type, haploid, homologous chromosome, interference, DNA, unequal crossing over, exon, degenerate code, PCR, peptide motif, aneuploid, Fitness, heritability, genetic drift

 

 

 

 

 

 

 

 

8. In the galactose operon in E. coli, a repressor, encoded by the galR gene, binds to an operator site, o, to regulate expression of three structural genes, galE, galT, galK. Expression is induced by the presence of galactose in the media. For each of the merodiploids listed below, would the cell show constitutive, inducible or no expression of each of the structural genes (galE, galT, galK)? Assume that galR- is a loss of function mutation). 8pts.

a.       galR-, o+,  galE+, galT+,  galK+/ galR-, o+,  galE+, galT+, galK+

b.      galR+, oc, galE+, galT+, galK+/ galR+, oc, galE+, galT+, galK+

c.       galR-, o+, galE+,galT+ galK-/galR+, o+, galE-, galT+, galK+

d.      galR+, oc, galE+, galT+, galK-/ galR+, o+, galE-, galT+, galK+

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2. Briefly describe the importance of and key methods used in  5 of the following 7 experiments (you should be able to do each part of this in less than 10 words!). 20 pts.

 

A. Bridge’s work with Nondisjunction and eye-color in Drosophilia

 

 

 

 

 

 

B. Lederbergs’ work with replica plating

 

 

 

 

 

 

C. Beadle and Tatum’s work with Neurospora.

 

 

 

 

 

 

D. Hershey and Chase experiments with phages

 

 

 

 

 

 

E. Mendel’s work with peas.

 

 

 

 

 

 

F. Messelson-Stahl experiement with bacteria grown in different N15-N14 mediums.

 

 

 

 

 

 

 

G. Corren’s 1909 work with green and variegated geraniums

 

 

 

3.. If the somatic cells of an organism has 6 chromosomes (total 4 points),

 

A. How many pairs of homologous chromosomes does it have? 2 pts

 

 

 

B. How many chromatids will be generated during meiosis? 2 pts

 

 

 

4. The below ratios were observed in the F2 of a cross between two lines that were homozygous and differentiated at two loci (e.g., AAbb x aaBB). Which of the ratios demonstrate independent assortment? (3 pts).

 

a. 9:3:3:1

 

b. 9:7

 

c. 9:3:4

 

d. 13:3

 

e. none of the above

 

f. a, b, c and d.

 

 

 

5. In corn, the genes l (little), b (black), and r (round) are all on chromosome 1. From the data summarized below that represent Test Cross Progeny:

 

a. determine the parental genotypes used to make the F1 (2 pts)

 

 

b. determine the order of the genes on the chromosome (4 pts)

 

 

 

YOU DO NOT NEED A CALCULATOR FOR THIS

Genotypes:

 

+r+/brl                                                             21

brl/brl                                                               2

b++/brl                                                 88

++l/brl                                                  339

+rl/brl                                                               55

br+/brl                                                              355

+++/brl                                                            2

b+l/brl                                                              17

Total                                                                879

 

6. Loci A and B are located 55 cM apart from one another on the same chromosome. Parantals AAbb and aaBB are crossed to make a AaBb F1. The AaBb F1 are test-crossed to aabb individuals. List the genotypes of the progeny and their percentage frequency. (6 pts)

 

 

 

 

 

 

 

 

 

 

 

 

7. List 2 types of mutations that result in no phenotypic change or no change in the amino acid sequence of a particular protein (4 pts)



 

 

 

 

 

 

 

8. Explain the difference between a locus and an allele (3 points)

 

 

 

 

 

 

 

 

 

 

 

9. Differentiate Phenotype from Genotype (4 pts). Be sure to list those factor(s) that contribute to a phenotype.

 

 

 

 

 

 

 

 

 

 

10. You make a cross between a red flowered plant and a white flowered plant. The red flowered plant supplies the pollen (acts as the male) and the white flowered plant supplies the eggs (is the female). You observe that all of the F1 progeny are white flowered. List the two most likely reasons that all of the F1 are white flowered (4 pts). Describe an experimental protocol to determine which of these two explanations best describes the mode of inheritance of flower color (3 pts).

 

 

 

 

 

 

 

 

 

 

 

 

12. Make a diagram showing the DNA and proteins involved in Eukaryotic gene expression. 6 pts. Include:

DNA, TAF, TBP, TATA Box, Enhancer DNA, and Activator factors

 

 

 

 

 

 

 

 

 

Equations that you may find useful:                

 


w = p2w1 + 2pqw2 + q2w3;                q = pq[q(w3-w2) + p(w2-w1)]/w            p2 +  2pq   + q2  =  1

 


Fitness of heterozygote > both homozygotes: The equilibrium gene frequency of   q   = s1/(s2 +s1)

 

13. What does the (2) or squared term represent in the Hardy-Weinberg equation?  (3 pts).

 

 

 

14. When artificial selection is imposed on a population, after a number of generations, phenotypes are observed that are more extreme than the phenotypes in the original population. This appears counter to the expectation of mendelian genetics where the extremes are governed by the appearance of either of the alternative homozygotes (AA or aa). What 3 factors can account for selection resulting in phenotypes more extreme than found in the original population  and are compatible with both natural selection and mendelian genetics. 6 pts.

 

 

 

 

 

 

 

 

 

15. You might find this useful:            R = h2S

 

A. You are a breeder, trying to breed for decreased size of chickens raised in xeric (dry) conditions, e.g., Sahel in Africa. You measure the heritability of size in conditions simulating these extreme dry conditions and quantify a heritability of 0.5. Size among your chickens ranges from 0.5-2.5 kilos. The mean of the population before selection is 2 kilos, and the mean of the chickens that you allow to breed to produce the next generation is 1 kilo.

 

i. What is S or the selection coefficient that you, the breeder have exerted on the population? (2 pts)

 

 

 

ii. What is the predicted mean weight of chickens in the next generation? (2 pts)

 

 

 

 

 

B. A heritability of 0.5 for weight indicates

i.  what variables are contributing to weight variation in the population? (2 pts)

 

 

 

 

ii. and in what relative proportions? (2 pts)

 

16. The genotypes SS, Ss and ss are associated with the expression of sickle-cell anemia, Ss are carrier and ss individuals express the disease. You blood type 100 infants in a particular village of West Africa and find 100 individuals of each genotype. You come back 20 years later and observe that of the 100 SS individuals, 10 have died from malaria, of the 100 Ss individuals, all are living, and 50 of the ss individuals have died from complications associated with the sickle-cell trait. For this population:

 

What is the fitness of each genotype, SS, Ss, ss (3 pts):

 

 

 

 

What is the selection coefficient associated with each genotype (3 pts)

 

 

 

What is the mean fitness of the population (3 pts)

 

 

And what is the equilibrium frequency of the big S allele  that you predict, NOTE that the frequency of the big S  allele corresponds to p (3 pts)?

 

 

 

 

 

 

17. PU is a particularly obnoxious disease, resulting in the emission of highly noxious body odor. The expression of this disease is due to a genetic disorder associated with a recessive mutation and is expressed only in homozygous recessive individual. If 1/10,000 or 1 in ten thousand individuals are born with this disease,

 

A. What is the frequency of the wild type dominant allele in the population (3 pts)? Show all work.

 

 

 

 

 

B. What is the frequency of carriers in the population? (3 pts) Show all work.

 

 

 

 

 

 

 

 

 

 

 

18. In the Lac operon there is a promoter and an operator. Distinguish the two in terms of location (same or different), what binds to them, and the consequences of a mutation in the promoter and in the operator (6 pts).

 

 

 

 

 

 

 

 

 

19. Working in the Andes Mountains of South America, you notice that a small fraction of native people suffer from symptoms very similar to altitude sickness. The symptoms seem to be predicted by pedigree, or are associated by family. Based on the pedigree analysis, you suspect a single mutation involved in the expression of the disease. List the steps that you might use to identify the gene in which the mutation is associated (8 pts).