BCH 369 EXAM 3 QUESTIONS WITH ALL REVISED ANSWERS
1 Which of the following types of RNA undergo post-transcriptional modifications?
a. mRNA
b. rRNA
c. tRNA
d. All of the above
e. None of the above - Answer-d
2 Which of these terms does not describe the DNA strand used to direct RNA synthe...
BCH 369 EXAM 3 QUESTIONS WITH
ALL REVISED ANSWERS
1 Which of the following types of RNA undergo post-transcriptional modifications?
a. mRNA
b. rRNA
c. tRNA
d. All of the above
e. None of the above - Answer-d
2 Which of these terms does not describe the DNA strand used to direct RNA
synthesis?
a. Template strand
b. Coding strand
c. Antisense strand
d. Negative or "−" strand
e. All these terms describe the DNA strand used to direct RNA synthesis - Answer-b
3 RNA synthesis begins at the base in the DNA sequence designated by the following
number:
a. +1 (plus one)
b. 0 (zero)
c. −1 (minus one)
d. −10 region (minus ten)
e. It varies between genes. - Answer-a
4 Initiation of RNA biosynthesis involves
a. recognition of the promoter region by the α subunit of RNA polymerase
b. conversion of the closed-promoter complex to the open-promoter complex
c. binding of one of the α subunits of RNA polymerase to each strand of DNA
d. incorporation of four pyrimidine nucleotides in succession - Answer-b
5 The majority of protein synthesis occurs in the
a. nucleus
b. mitochondrion
c. cytoplasm
d. nucleolus - Answer-c
6 At which position on the mRNA is the wobble base of the triplet codon?
a. first position (5' letter)
b. second position
c. third position (3' letter)
d. the wobble base can be at any position - Answer-c
,7 An aminoacyl-adenylate contains
a. an ester bond
b. an acid anhydride bond
c. an amide bond
d. an ether bond - Answer-b
8 After peptide bond formation takes place, what step is necessary for continuation of
protein synthesis?
a. binding of uncharged tRNA to the ribosome
b. binding of EF−Tu
c. binding of EF−Ts
d. translocation of the ribosome - Answer-d
9 The application of gel electrophoresis (PAGE) in DNA sequencing
a. is nonexistent because DNA fragments differ widely in charge.
b. depends on separation of similar charge/mass ratio on the basis of size.
c. depends on separation of identical size on the basis of charge/mass ratio.
d. is nonexistent because DNA fragments have no net charge. - Answer-b
10 SyBr green and SyBr gold were developed because
a. ethidium bromide is not sensitive enough for modern research
b. they allow faster electrophoretic separations of DNA
c. they fluoresce with RNA as well as DNA, while ethidium bromide does not
d. ethidium bromide is carcinogenic - Answer-d
11 Antibiotic-resistance genes in vectors are often used as selectable markers.
a. True
b. False - Answer-a
12 What is the function of protein spikes on a virus?
a. They protect the genome.
b. They are involved with incorporation of the genome into that of host (lysogeny).
c. They transcribe the RNA genome into a DNA copy.
d. They help the virus attach to the host. - Answer-d
13 Antibodies are the most variable protein sequences in the human body.
a. True
b. False - Answer-a
14 The term antibody is essentially interchangeable with
a. immunoglobulin.
b. reverse transcriptase.
c. allergen.
d. vaccine. - Answer-a
15 Which type of interactions predominate for sequence-specific DNA-binding proteins?
,a. hydrogen bonding
b. van der Waals interactions
c. electrostatic interactions
d. A and B
e. A, B and C - Answer-d
16 Which of the following RNA transcript sequences (read 5 ́ to 3 )́ contains an E. coli
transcription terminator?
a. NNAACCCCCCNNNNCCCCCCUUUUUU
b. NNAAGGGGGGNNNNGGGGGGAAAAAA
c. NNAAGGGGGGNNNNGGGGGGUUUUUU
d. NNAAGGGGGGNNNNCCCCCCUUUUUU - Answer-d
17 _____ are eukaryotic DNA sequences that can be used to elevate transcription and
have variable positions and orientations.
a. Enhancers
b. Operators
c. Introns
d. Polycistrons
e. Promoters - Answer-a
18 The enzyme principally responsible for RNA synthesis in Escherichia coli
a. is a multisubunit enzyme
b. consists of a single polypeptide chain
c. requires Mn2+ for activity
d. requires a DNA primer - Answer-a
19. Which of the following is not a property of the sigma (σ) subunit?
a. It tells the RNA Polymerase where to sit down.
b. It helps point the RNA Polymerase in the proper direction.
c. It causes the RNA Polymerase to bind fairly tightly to the DNA.
d. It stays with the RNA Polymerase throughout synthesis. - Answer-d
20. What provides the energy for rho-dependent chain termination?
a. ATP hydrolysis distinct from any incorporation into the chain.
b. Nucleotide hydrolysis associated with incorporation into the chain.
c. Torsional stress built into the separating DNA strands.
d. There is no energy requirement. - Answer-a
21. Cyclic AMP affects transcription by
a. triggering the action of several protein factors
b. phosphorylating a subunit of RNA polymerase
c. phosphorylating a transcription factor
d. inhibiting DNA loopinge. None of these - Answer-a
22. Inducers allow for a system in which an enzyme is not made unless it is needed.
, a. True
b. False - Answer-a
23. In the two-step process of charging tRNAs, the ___ bond between AMP and the
amino acid is exchanged for a(n)___ bond between tRNA and the amino acid.
a. phosphoester; phosphoester
b. phosphoester; ester
c. ester; phosphoester
d. phosphodiester; amide
e. phosphodiester; ester - Answer-b
24. Which statement is part of the wobble hypothesis?
a. The 5' anticodon base can pair with several different 3' codon bases.
b. The middle codon base can pair with several different middle anticodon bases.
c. The 3' anticodon base can pair with several different 5' codon bases.
d. The 5' codon base can pair with several different 3' anticodon bases. - Answer-a
25. EF-Tu binds all 20-aminoacyl tRNAs with equal efficiency, except formyl-Methinone-
tRNA (fMet-tRNA). Whywould it be a bad thing if EF-Tu bound fMet-tRNA and delivered
it to the ribosome?
a. incorporation of fMet might change the properties of the protein
b. fMet cannot form a peptide bond
c. fMet may react with rRNA at the peptidyl transferase site
d. fMet bound to EF-Tu would prevent EF-Ts from binding to EF-Tu
e. none of the above - Answer-b
26. Why do amino acids other than methionine occur in the N-terminal position of
proteins from eukaryotes?
a. AUG is not the start codon in eukaryotes.
b. Proteins from eukaryotes are subject to post-translational modifications.
c. The genetic code is not the same in prokaryotes and eukaryotes.
d. The N-terminal amino acid in eukaryotes is fmet - Answer-b
27. How many codons are known for each amino acid?
a. 1 only
b. 2 only
c. 2 to 4 depending on the nature of the amino acid
d. 1 to 6 depending on the nature of the amino acid - Answer-d
28. Which of the following statements concerning tRNAs is false?
a. They have distinctive cloverleaf tertiary structures
b. They are unique in that they are transcribed by DNA polymerases
c. They contain many modified nucleobases
d. They contain the anticodon sequence - Answer-b
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