2.) _Below is a copy of an electron micrograph we discussed in lecture. This figure depricts a brief second in the life of a cell. Use thia figure to answer the following questions: (8 points)

All multiple choice worth 3 pts each

1.) Refer to the list of proteins below to answer the following questions. (10 pts)

a. helicase

b. single-stranded binding proteins.

c. DNA polymerase

d. ligase

e. primase

f. RNA polymerase

NOTE: there may be more than one correct answer from the list above for each of the 5 questions below. The answers may be used once, more than once, or not at all.

i. catalyzes the synthesis of a new DNA strand by the addition of deoxyribonucleotides in a 5'--->3' direction .

ii. enhances the separation of DNA strands during replication .

iii. covalently connects segments of DNA .

iv. only synthesizes short segments of RNA .

v. requires a 3' OH for the addition of new nucleotides on a growing chain .

2. What kind of chemical bonds are found between paired bases of the DNA double helix?

a. hydrogen

b. ionic

c. covalent

d. sulfhydryl

e. phosphate

3. A eukaryotic cell lacking telomerase would

a. be unable to initiate DNA synthesis on lagging strands

b. have a greater potential to become cancerous

c. be unable to identify mismatched nucelotides in its daughter strands

d. experience a gradual reduction of chromosome length with each replication cycle

e. be unable to uptake DNA from the surrounding solution

4.) Below is a copy of an electron micrograph we discussed in lecture. This figure depicts a brief second in the life of a cell. Use this figure to answer the following questions: (10 points)

a.) Is this taking place in a prokaryote or eukaryote? How do you know? (2 pts)

b.) On the figure, indicate the 5' and 3' ends of both DNA strands. (2 pt)

c.) How many transcripts are currently being made (i.e. how many RNA polymerases are active at this moment). (1 pt)

d.) Are these transcripts most likely mRNA, tRNA, or rRNA? How do you know?(2 pt)

e.) On the figure, indicate the approximate location of the promoter on the correct strand (1 pt).

f.) On the figure, indicate direction of transcription and translation (2 pts)

5. Transcribe and translate the following

piece of DNA. Indicate the 5' and 3'

ends of the mRNA, and the amino

and carboxyl terminal ends of

the protein (4 pts/ea)

3' TACCGGTATCTACTTCG...5'

a. mRNA

b. Protein

c. Assuming this is a real gene encoding an

essential protein in a cell, what would be

the most likely effect on the cell if the

underlined G base was deleted by

mutation ? Explain your answer.

d.Assuming this is a real gene encoding an

essential protein in a cell, what would be

the most likely effect on the cell if the

underlined G base was changed to a T

by mutation ? Explain your answer.

6.) Explain in 2-3 sentences what an operon is. (5 points)

7.) Transcription of the structural genes in an inducible catabolic operon

a. occurs all the time

b. occurs only when the pathway's product is absent

c. occurs only when the pathway's substrate is present

d. stops when the pathways product is present

e. does not produce enzymes

8. Genetic regulation can occur at several levels in both prokaryotes and eukaryotes. For each level below, indicate whether it could work for prokaryotes (P), eukaryotes (E), both (B) or neither(N) (12 pts)

a. degradation of active protein

b. transcription

c. translation

d. mRNA processing

e. At which level shown above, would the cell be able to respond to a stimuli most rapidly?

f. A cell would best conserve cellular resources be regulating at which level (shown above)?

9. Which of the following statements concerning proto-oncogenes is FALSE?

a. They code for proteins associated with cell growth

b. They are similar to oncogenes found in retroviruses

c, They are produced by somatic mutations induced by carcinogenic substances

d. They are involved in producing proteins for cell adhesion

e. They are genes that code for proteins involved in cell division

10. Which of the following events is necessary for the production of a truly malignant tumor.

a. activation of an oncogene in the cell.

b. inactivation of tumor suppressor genes (such as p53 and APC) in cell

c. the presence of a mutagenic substance within the cell's environment

d. presence of UV similar to that found in sunlight

e. Both a and b are necessary

11. Darwin differed from Lamarck in his proposal that

a. species are not fixed

b. evolution leads to adaptation

c. life on earth has a long evolutionary history

d. life on earth did not evolve abruptly, but rather through a gradual process of minute changes

e. inherent variations in the population are more important in evolution than variations acquired during individual lifetimes.

12. Which of the following did Darwin NOT understand about natural selection?

a. that organisms become extinct

b. the source of genetic variation

c. that variation is common in populations

d. that competition exists in populations

e. that populations overproduce offspring

13.) Briefly (but accurately) explain the difference between natural selection and evolution. (no more than three sentences, please) (6 pts)

14.) A biologist studies a population of squirrels for 15 years. Over that time, the population was never fewer than 30 squirrels and never more than 45. Their data showed that over half the squirrels born did not survive to reproduce, because of competition for food and space. Suddenly, the population increased to 80. In a single generation, 90% of the squirrels that were born lived to reproduce. What inferences might you make about the population?

a. All of the below are reasonable inferences,

b. The amount of available food probably increased.

c. The number of predators probably decreased.

d. The young squirrels in the next generation will show greater levels of variation than in the previous generations because squirrels that would not have survived in the past are now surviving.

e. Both B and C are reasonable inferences.

15.)What are the five requirements for maintenance of Hardy-Weinburg equilibrium in a population? (5 pts)

16. Over a period of time, the frequency of an allele in a small population decreases from 0.01 to 0.003. Which of the following might explain this change?

a. The allele is disadvantageous when homozygous.

b. Migrants entering the population had a lower frequency of that allele than did current members of the population

c. One member of the population who was homozygous recessive for the trait accidentally died.

d. A and B are correct.

e. A, B and C are correct.

17. In peas, a gene controls flower color such that R = red and r = white. In an isolated pea patch, there are 64 white flowers and 36 red flowers. Assuming Hardy-Weinburg equilibrium, (6 pts)

a. determine the allele frequencies of the recessive and dominant alleles?

b. determine how many of the red flowers are heterozygous.

18. Using the information from question 17 above, suppose the environment changes such that RR flowers are no longer pollinated- i.e. they no longer reproduce. Assume Rr flowers are pollinated. In five generations, what would be the frequency of individuals with white flowers (rr)?

a. less than 0.04

b. 0.04

c. 0.32

d. 0.64

e. greater than 0.64

yee-haw!!!