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Name:
BIO 260: MICROBIOLOGY
QUIZ #3
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Multiple choice: Circle the letter of the ONE alternative that best completes the statement or
answers the question. Each question is worth 1 point.
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1. Which of the following macromolecules is an informational macromolecule?
A. Glycolipids
B. Polysaccharides
C. Deoxyribose nucleic acid
D. Phospholipids
E. Polyphosphate
2. The correct order of steps of the central dogma of molecular biology is:
A. Replication  Translation  Transcription
B. Translation  Transcription  Replication
C. Translation  Replication  Transcription
D. Transcription  Translation  Replication
E. Replication  Transcription  Translation
3. The primary structure of bases in DNA (and RNA) refers to:
A. The association of one or more strands by hydrogen bonding
B. The linear sequence of purines and pyrimidines
C. The complementary binding of purines and pyrimidines
D. Supercoiling
E. Double stranded helix
4. AT-rich DNA strands will denature (separate) at a(n):
A. Higher temperature than GC-rich DNA
B. Identical temperature as GC-rich DNA
C. Similar temperature as GC-rich DNA, with minor variations
D. Lower temperature than GC-rich DNA
E. Temperature dependent upon whether it is from a prokaryote or eukaryote
5. In prokaryotes, the enzyme that introduces negative supercoils into DNA by making doublestranded cuts is called:
A. DNA gyrase
B. RNA polymerase
C. DNA polymerase
D. Topoisomerase I
E. DNA twistase
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Short answer: Please PRINT your answer to the following questions in the space provided.
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6. Describe two major differences between DNA and RNA. (2 points)
7. Inverted repeats can give rise to stem-loops.
a. Show this by giving the sequence of a double-stranded DNA containing an inverted
repeat and show how the transcript can form a stem loop. (1 point)
b. Does the sequence 5’-GCACGGCACG-3’ contain an inverted repeat? Explain. (1
point)
8. Look at the single strand of DNA depicted at the right. (6 points)
a. What is the direction of the single strand shown below?
b. What would be the direction of the complementary strand?
c. What number carbon atom are the bases attached to?
d. Circle one of the deoxyribose molecules.
e. Indicate one of the phosphodiester bonds with an arrow.
f. Would the strand shown be a leading strand during
replication?
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9. What enzymatic activity, in addition to polymerization, is associated with DNA polymerase
III and how does it reduce errors during DNA replication? (2 point)
10. Describe the basic principles of gene amplification using the polymerase chain reaction
(PCR). (2 points)
11. The haploid genome of the causative agent of gonorrhea, Neisseria gonorrhea, is a bacterium
that contains 2220 kilobase pairs. If 85% of this DNA molecules is made up of open reading
frames of genes and the average protein is 300 amino acids long, how many protein-encoding
genes does Neisseria have? (2 points).
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