Name_________________________________________
October 9, 2006
BIO184 Genetics
Exam 1
This examination is worth 100 points. There are 28 questions on 7 pages. Read through the
questions completely before answering the questions. If you are unclear about a
question, please ask me. Show all of your work for workout problems.
Part A: Multiple Choice: Answer with the best choice. Make sure that you clearly circle the
correct answer and erase any erroneous marks. (2.5 pts each)
1. A + T = G + C
a) true
b) false
2. The building blocks of DNA are called __________.
a) amino acids
b) codons
c) nucleotides
d) alleles
3. The compacted 30 nm fiber of DNA is a structure comprised of all of the following
except for:
a)
b)
c)
d)
e)
heterochromatin
DNA wrapped around histones
“beads on string”
radial loops
both a and d
4. The fact that the type IIR and IIIS strains of Streptococcus pneumoniae that Griffith worked
with possessed small differences in capsule structure satisfies which of the following criteria
for genetic material?
a) transmission
b) replication
c) stores information
d) encodes variation
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5. You have isolated what appears to be alien DNA. While studying its replication, you
performed the exact experiment Meselson and Stahl did. After three generations, the DNA is
subjected to a CsCl gradient, and only one band appears. What type of replication does this
DNA undergo?
a) semiconservative
b) conservative
c) dispersive
6. What do both the rho-dependent and rho-independent mechanisms of termination have
in common?
a)
b)
c)
d)
Terminate transcription immediately after the stop codon.
Formation of a stem-loop structure.
Both require a helicase to separate the DNA-RNA complex.
A sequence rich with A-U base pairs.
7. A Cot curve can be used to determine _______.
a) the sequence complexity of a given organism (e.g. repetitive vs. unique DNA)
b) the total concentration of DNA in a cell
c) the number of origins of replication
d) the length of the chromosome in basepairs
8. Areas of the chromosome that remain highly condensed are called _________.
a) loop domains
b) facultative heterochromatin
c) constitutive heterochromatin
d) chromatids
e) euchromatin
9. Chargaff demonstrated that A pairs with T and C pairs with G by:
a)
b)
c)
d)
by peforming X-ray diffraction of DNA
by analyzing the nucleotide base composition of the DNA from different organisms
by generating a ball-and-stick model of DNA
by DNA sequencing
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10. Following transcription, the RNA has a complementary sequence of which of the
following?
a) regulatory sequences
b) termination sequences
c) the coding strand of DNA
d) the template strand of DNA
e) none of the above
11. Which of the following is not true about DNA polymerase?
a) it cannot begin at the 5’end of a new strand without a primer
b)
c)
d)
e)
it can only travel in the 5’ to 3’ direction
it can extend the 3’ end of a DNA strand in the absence of a complementary strand
it can replace a RNA primer with DNA
it can synthesize DNA from the 3’ end of an RNA oligonucleotide
12. The complementary sequence of 5’AATTCGCTTA 3’ is:
a) 5’ AATTCGCTTA 3’
b) 3’ AATTCGCTTA 5’
c) 5’ TAACGCTTAA 3’
d) 5’ TAAGCGAATT 3’
e) 5’ TTAAGCGAAT 3’
13. From DNA research, sites of transcription and therefore most of the genes along the
length of the chromosome appear to be found in:
a)
b)
c)
d)
heterochromatin
euchromatin
constitutive heterochromatin
centromeric regions
14. The ability for normal somatic cells to divide indefinitely is likely attributed to:
a) After 30-50 cell divisions, the cells rejuvenate and regain their capacity for cell division
b) Telomerase becomes active within the cell
c) Telomeres shorten slightly with each cell division
d) Cells shorten the cell cycle and go into the DNA synthesis phase much faster
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15. Which of the following is incorrect regarding the Hershey-Chase experiments?
a) They radioactively labeled the protein coat of the bacteriophage with 35S.
b) They radioactively labeled the DNA of the bacteriophage with 32P.
c) The results of the experiment indicated the presence of 32P remained in the cell.
d) The results of the experiment indicated that most of the 35S remained in the cell.
e) Their results suggested that DNA is the genetic material.
16. Alternative splicing allows an organism to ____________.
a)
b)
c)
d)
e)
carry fewer genes
carry more genes
produce fewer gene products
replicate faster
both a and c
17. Two DNA sequences (A and B) of the same length, have melting temperatures,
respectively, of 73º C and 81º C. What can be concluded about the base composition of these
two DNAs?
a) Sequence A has more repetitive DNA within it
b)
c)
d)
e)
Sequence A has less repetitive DNA within it
Sequence A has a higher percentage of A/T nucleotides within it
Sequence A has a higher percentage of G/C nucleotides within it
none of the above
PART C - Answer the following questions as True or False. If false, fix the statement.
(2.5 pts each)
18. Most eukaryotic genes are colinear.
19. The only difference between DNA and RNA is that RNA uses Uracil instead of Thymine.
20. Okazaki fragments are comprised solely of single stranded DNA oligonucleotides
synthesized during replication.
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21. DNA is a right-handed double helix in parallel direction.
22. Following transcription, the RNA has a complementary sequence to the template strand
of DNA.
Part C: Short answer. Please write clearly. Use the back of the sheet for extra space.
23. A nucleosome is a combination of ____________ and ______________.
(3 pts)
24. How is the process of transcription in eukaryotic cells different from that in bacterial cells?
(note: be sure to cover the complete process from initiation to completion of a mature
transcript)?(8 pts)
25. How is the process of eukaryotic replication different from bacterial replication? (hint: two
major differences). In your answer, explain why they are different. (8 pts)
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26. What would be the effect on DNA replication of mutations that destroyed each of the
following activities in DNA polymerase?(6 pts)
a. 3’  5’ exonuclease activity
b. 5’  3’ exonuclease activity
c. 5’  3’ polymerase activity
27. Explain in detail how the following components are involved in bacterial replication for
both the leading and lagging strands. (10 pts)
gyrase, helicase, DNA polymerase I, DNA polymerase III, DNA primase, ligase,
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28. Using the provided template of the Avery, MacLeod and McCarty experiment: (10 pts)
a) Describe their results (and/or draw).
b) What was their conclusion?
c) Label which particular trials were controls (negative or positive) or experimental
treatments.
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Answers:
1. B
2. C
3. E
4. D
5. C
6. B
7. A
8. C
9. B
10. D
11. C
12. D
13. B
14. B
15. D
16. A
17. C
18. false, prokaryotic
19. false, also ribose instead of deoxyribose
20. false, RNA-DNA hybrid
21. false, antiparallel
22. true
23. histones and DNA
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