Download BB451 Spring 1987 Midterm 2 Name

Answers: A C B E B C D E C C B C D A B C A C B B E C E E A C E B
E B B A D C D D A (ABCDE) A E E A B C D D B D C E D A A D D C
B C A B B C B C D A (BC) B C D B C B B A
NOTE: question #38 everyone was awarded a mark (all answers were
excepted as correct) and question #67 both B and C were correct.
The following questions 1 through 26 are based on Section 1 lectures:
1. Which of the following is not a general structural feature of a nucleotide?
a) A phosphate is attached to the 2’ hydroxyl of ribose.
b) A purine or pyrimidine ring nitrogen atom is attached to the 1' carbon atom of
ribose.
c) A hydroxyl group is attached to the 3' carbon atom of ribose.
d) A hydrogen atom or hydroxyl group is attached to the 2' carbon atom of ribose.
e) The phosphate is negatively charged at neutral pH.
2. Which of the following is not correct concerning the structure of RNA?
a) The monomer units used for polymerization are ribonucleoside triphosphates.
b) The monomer units are linked by phosphodiester bonds.
c) The bridge between adjacent nucleotides involves two phosphate atoms.
d) The bridge between adjacent nucleotides involves the 5' carbon and 3' carbon of
adjacent subunits.
e) The 2' carbon atom of each subunit contains a hydroxyl group.
3. In which of the following DNA duplexes would complementary bases dissociate at
the lowest temperature?
a) 5'-GCGCGCGC-3'
3'-CGCGCGCG-5'
b) 5'-ATATATAT-3'
3'-TATATATA-5'
c) 5'-GATCGATC-3'
3'-CTAGCTAG-5'
d) 5'-GGGGAAAA-3'
3'-CCCCTTTT-5'
e) 5'-GGGGGGGG-3'
3'-CCCCCCCC-5'
4. The nitrogenous base shown is:
a) thymine
b) uracil
c) adenine
d) cytosine
e) guanine
5. If an antibiotic prevents the translocation of prokaryotic ribosomes, which of the
following best describes the state of the ribosome in the cells exposed to the
antibiotic? Note: Charged = with amino acid; uncharged = without amino acid.
a) P site contains peptidyl tRNA, A site contains aminoacyl tRNA.
b) P site contains uncharged tRNA, A site contains peptidyl tRNA.
c) P site contains peptidyl tRNA, A site contains uncharged tRNA.
d) P site contains aminoacyl tRNA, A site contains aminoacyl tRNA.
e) P site contains uncharged tRNA, A site contains aminoacyl tRNA.
6. If an antibiotic inhibits the activity of elongation factor EF-Tu, which of the following
best describes the status of the ribosomes in prokaryotic cells exposed to the drug?
Note: Charged = with amino acid; uncharged = without amino acid.
a) P site contains peptidyl tRNA, A site contains aminoacyl tRNA.
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b) P site contains uncharged tRNA, A site contains peptidyl tRNA.
c) P site contains peptidyl tRNA, A site with no aminoacyl tRNA.
d) P site contains aminoacyl tRNA, A site contains aminoacyl tRNA.
e) P site contains uncharged tRNA, A site contains aminoacyl tRNA.
7. Which of the following is not correct?
a) Each aminoacyl tRNA synthetase reaction requires ATP.
b) The anticodon loop is important for tRNA recognition by aminoacyl tRNA
synthetases.
c) Each specific aminoacyl tRNA synthetase recognizes only one amino acid.
d) Each aminoacyl tRNA synthetase recognizes only one tRNA.
e) Amino acids are attached to their cognate (specific) tRNA.
8. Which of the following statements concerning DNA replication initiation in E. coli is
not correct?
a) The E. coli chromosome has a single replication origin termed oriC.
b) OriC is about 240 base pairs long and contains four 9 base pair repeats that are
bound by a cluster of DnaA proteins.
c) The DNA wraps around the DnaA cluster, which helps “melt” local AT-rich
repeats.
d) The “melted” region serves as a binding location for Helicase.
e) Unlike Okazaki fragments, a RNA primer is not required to initiate leading strand
synthesis.
9. When E. coli is grown for 500 generations in N15, a heavy isotope of nitrogen, and is
subsequently transferred for one generation to N14, the normal isotope of nitrogen, all
of the DNA isolated from the E. coli had an intermediate density between that formed
with N15 and that formed with N14 when analyzed by cesium chloride density
ultracentrifugation. Which of the following models of DNA replication did the above
result demonstrate to be incorrect?
a) Semiconservative replication.
b) Dispersive replication.
c) Conservative replication.
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d) Dispersive and conservative replication.
e) Dispersive and semiconservative replication.
10. DNA polymerase III occurs in E.coli. Theoretically, how may DNA polymerase III
molecules should be required for the entire E. coli chromosome to be replicated?
a) One.
b) Two.
c) Four.
d) About 100.
e) About 1,000.
11. Choose the statement (a-e) that correctly completes the following:
Eukaryotic organisms have linear chromosomes and use a special mechanism to
extend the lagging strand template ends because
a) DNA polymerases cannot extend the lagging strand to completion at the 3’ end.
b) DNA polymerases can only polymerize deoxynucleotides at the 3' end of existing
strands.
c) there is more than one eukaryotic DNA polymerase.
d) eukaryotic DNA polymerases can not reach the end of the chromosome.
e) replication is bi-directional.
12. Which of the five possible answers (a-e) below correctly completes the following
phrase?
The RNA component of telomerase
a) is an RNA primer used to extend the lagging strand template.
b) is used as a primer to initiate synthesis of the last Okazaki fragment of the lagging
strand.
c) is a template used to extend the lagging strand template.
d) is used as a primer to elongate the leading strand template.
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e) serves as a primer to initiate synthesis of the leading strand.
13. With which of the following anticodons below would the codon 5'-ACG-3' pair?
a) 5'-UGC-3'
b) 5'-TGC-3'
c) 5'-CGT-3'
d) 5'-CGU-3'
e) 5'-GCA-3'
14. Which of the following concerning transcription by RNA polymerase II is not
correct?
a) The TATA box binding protein (TBP) dissociates from the RNA polymerase II
after phosphorylation of the carboxy-terminal domain (CTD) of the polymerase.
b) RNA polymerase II recognizes DNA by binding to the TATA box binding
protein-TF IIB complex at the TATA box.
c) The RNA polymerase II has an unphosphorylated carboxy-terminal domain when
it forms the preintiation complex.
d) Transcription factor TFIIH binds with the preintiation complex to form the
transcription-initiation complex.
e) RNA polymerase II elongates a molecule of mRNA after phosphorylation of the
carboxy-terminal domain.
15. Which of the following is the most likely situation within the ribosome immediately
after the peptidyl transferase reaction? Note: Charged = with amino acid; uncharged =
without amino acid.
a) P site contains peptidyl tRNA, A site contains aminoacyl tRNA.
b) P site contains uncharged tRNA, A site contains peptidyl tRNA.
c) P site contains aminoacyl tRNA, A site contains peptidyl tRNA.
d) P site contains peptidyl tRNA, A site contains uncharged tRNA.
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e) P site contains aminoacyl tRNA, A site contains uncharged tRNA.
16. Which of the following occurs first during DNA replication initiation in E. coli?
a) Primase synthesizes a RNA primer.
b) Single strand binding protein (SSB) coats single-stranded DNA.
c) A specific region of the E. coli chromosome wraps around a cluster of DnaA
polypeptides.
d) DnaC loads the enzyme helicase onto the DNA template.
e) Helicase melts the DNA duplex.
17. What is the role of the beta subunit of DNA polymerase III?
a) It clamps around the DNA, and allows the polymerase to become “processive”.
b) It dissociates the DNA double helix at complementary base pairs.
c) It acts as a hinge.
d) It has pyrophosphatase activity and yields two phosphate molecules from
pyrophosphate.
e) It hydrolyzes ATP to drive deoxynucleoside triphosphate polymerization.
18. Which enzyme catalyzes phosphodiester bond formation between two adjacent
Okazaki fragments after the primers have been removed and the gap has been filled
with appropriate nucleotides?
a) DNA polymerase III.
b) DNA polymerase  (alpha).
c) DNA ligase.
d) DNA polymerase I.
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e) DNA polymerase  (delta).
19. The codon 5'-AUC-3' pairs with which of the following anticodons?
a) 5'-UGC-3'
b) 5'-IAU-3', 5’-GAU-3’
c) 5'-GIT-3’
d) 5'-CGU-3', 5’-GII-3’
e) 5'-NOT-3', 5’-ITT-3’
20. Consider the following piece of eukaryotic RNA:
3’-AUCCUGAAUUAGA-5’
If you synthesize the complementary DNA single strand to the above piece of RNA,
and hybridize the synthetic DNA strand to each of the following five DNA fragments,
which hydrid duplex would have the highest melting temperature (Tm)?
a) 5’-AAGTCCT-3’
b) 5’-TAAGTCCT-3’
c) 5’-TAAGTCC-3’
d) 5’-ATTAAGTC-3’
e) 5’-TCCTGAATT-3’
21. Which of the following concerning eukaryotic mRNA processing is not correct?
a) A Poly (A) signal occurs approximately 10-35 nucleotides upstream of the
polyadenylation (poly A) site.
b) Efficient cleavage and polyadenylation of pre-mRNA requires a GU-rich region
downstream of the Poly (A) signal.
c) A cleavage and polyadenylation specificity factor (CPSF) forms an unstable
complex with the Poly (A) signal.
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d) A cleavage stimulatory factor (CStF) and two cleavage factors, (CF I) and (CF II),
bind the CPSF-RNA complex.
e) Polyadenylation of the pre-mRNA with up to 200 to 250, or more (A) subunits
occurs in a single phase using the enzyme Poly (A) polymerase (PAP) working
alone.
22. Which of the following concerning intron splicing of pre-mRNA is not correct?
a) All introns have 5’-GU, 3’-AG splice sites, and an (A) residue at the branch
point.
b) U1 small nuclear RNA (U1 snRNA) binds the 5’-GU bases of an intron by
complementary base pairing.
c) U2 snRNA directly binds by complementary base pairing the 3’-AG splice site
bases.
d) U2 snRNA binds with several intron bases at the branch point near the 3’ end of
an intron but does not base pair with the 3’-AG splice site bases.
e) U1, U2, U4,U6 and U5 form a complex called a spliceosome.
23. Which of the following concerning bacterial initiation of protein synthesis is not
correct?
a) Initiation factors, IF1, IF3 and IF2-GTP bind the 30s ribosomal subunit to form
the Preinitiation complex.
b) The Shine-Dalgarno sequence interacts with the 16S ribosomal RNA.
c) When mRNA + formyl-Methionine-tRNA i Met bind to the 30s Preinitiation
complex, IF3 is displaced and the 30s Initiation complex is formed.
d) Binding of the 50s ribosomal subunit to the 30s Initiation complex displaces IF1,
IF2-GDP + Pi and yields the 70s Initiation complex.
e) Translation of E. coli mRNA begins when the formyl-Methionine-tRNA i Met is in
the A site within the ribosome of the 70s Initiation complex.
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24. Which of the following is not a general characteristic of non-standard base pairing
between codons and anticodons?
a) When the bases, C, A, or G are in the first, or wobble, position (5’3’) of the
anticodon, then the tRNA may recognize, the bases, G, U, or C, respectively, in
the third position (5’3’) of a mRNA codon.
b) When the base Inosine (I) is in the first, or wobble, position (5’3’) of the
anticodon, then the tRNA may recognize, the bases, C, A, or U in the third
position (5’3’) of a mRNA codon.
c) When the base U is in the third, or wobble, position (5’3’) of the mRNA, then
the codon may be recognized, by a tRNA having the bases, A, G, or I in the first
position (5’3’) of the anticodon.
d) When the base C is in the third, or wobble, position (5’3’) of the mRNA, then
the codon may be recognized, by a tRNA having the bases, G or I in the first
position (5’3’) of the anticodon.
e) When the base I is in the third, or wobble, position (5’3’) of the mRNA, then
the codon may be recognized, by a tRNA having the bases, A, G, or I in the first
position (5’3’) of the anticodon.
25. In in vitro replication of SV40 DNA by eukaryotic enzymes, which of the following
is not correct.
a) Opening of the replication forks at the SV 40 origin requires 9 mers and 13 mers
that are bound by T-antigen.
b) DNA polymerase alpha is associated with a primase, and initiates leading strand
synthesis 5'3’ from an RNA primer made by primase.
c) Binding of proliferating cell nuclear antigen (PCNA) to replication factor C
(RFC) displaces DNA polymerase alpha-primase complex in leading strand
synthesis.
d) Lagging-strand DNA synthesis down-stream from the leading strand primers is
occurs by the action of DNA polymerase alpha-primase.
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e) The DNA polymerase delta-PCNA-RFC complex is involved in completion of the
leading strand after polymerase alpha-primase is displaced by PCNA.
26. Which of the following concerning E. coli RNA polymerase is not correct?
a) It is an enzyme consisting of two types of Beta subunits (beta and beta1), an alpha
subunit and a sigma subunit.
b) The core enzyme is composed of two alpha subunits joined with beta and beta 1
subunits.
c) In the absence of sigma 70 factor the core RNA polymerase binds the -10, -35
promoter regions upstream of the transcription site as well as the transcription
initiation (+1) site and transcribes the DNA to completion.
d) The consensus sequences of the (-35) and (-10) promoter regions are believed to
include the sequences, TTGACAT and TATAAT, respectively.
e) Sigma 70 is required to lead the RNA polymerase to the correct promoter site.
The following questions 27 through 52 are based on Section 2 lectures:
The following is a diagram of double-stranded prokaryotic DNA and should be used to
answer questions 27 to 29. All start and stop codons are indicated.
27. Shine Dalgarno sequences would be located at which of the following letters?
a) A only
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b) B only
c) E only
d) A, B, C, and D
e) B, C, and D
28. If the DNA in the diagram was transcribed and translated, which of the following
would be the correct observation?
a) The mRNA transcribed would be an exact copy of the top DNA strand.
b) One mRNA and three proteins would be produced.
c) In this complex transcriptional unit, all of the proteins produced are coded by one
gene.
d) RNA polymerase would bind first at position “B” on the DNA.
e) Regions indicated by “C” and “D” would be spliced out of the final mRNA
transcript.
29. What is the name for the region between the start site of transcription and the first
ATG?
a) Promoter.
b) 3’ untranslated region.
c) Start site for translation.
d) Polyadenylation signal.
e) 5’ untranslated region.
30. The operator region on the lactose operon is an example of a
a) repressor.
b) cis-acting regulatory element.
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c) trans-acting regulatory element.
d) trans-acting protein.
e) regulon.
31. The following is a diagram of a sequencing gel. What is the sequence of the DNA
that was used as the template in the sequencing reaction?
a) 5’ ACC AGG TGT 3’
b) 5’ ACA CCT GGT 3’
c) 5’ TGG TCC ACA3’
d) 5’ TGT GGA CCA 3’
e) 3’ ACC AGG TGT 5’
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32. Automated sequencing is based on the original Sanger (Dideoxy) chain termination
method. Which of the following is found in both methods?
In both methods,
a) dideoxyribonucleoside triphosphates (ddNTP) are used.
b) different fluorescently labelled deoxyribonucleoside triphosphates (dNTPs) are
used.
c) the primer is labelled either with radioactivity or with fluorescent molecules.
d) four reaction tubes are required.
e) the labelled products of the sequencing reaction are detected by autoradiography.
33. You sequence the lac operon from the genome of a bacterium and find that there is a
mutation in the lac operator sequence that prevents the binding of the lac repressor.
Which of the following observations or experiments concerning this bacterium with
the mutant lac operon is correct?
a) The binding of RNA polymerase to its site on the mutant lac operon would be
reduced.
b) The function of the lac operator could be restored by transfection with a plasmid
containing a normal lac operator.
c) If the mutant bacterium was cultured in glucose only, the amount of galactosidase would be lower than that found in a normal bacterium under the
same conditions.
d) If the mutant bacterium was cultured in lactose only, the amount of galactosidase would be the same as that found in a normal bacterium under the
same conditions.
e) The mutant bacterium would not be able to survive in medium that contained only
lactose.
34. What happens when the lac repressor protein is bound to allolactose?
a) Transcription of the lac operon is inhibited.
b) The lac repressor blocks the binding of CAP.
c) Transcription of the lac operon may be below maximal levels.
d) The lac repressor protein exists as a dimer.
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e) The lac repressor has high affinity for RNA polymerase
35. Cyclic AMP (cAMP)
a) binds to allolactose.
b) interacts with the -subunits of RNA polymerase.
c) binds to the operator sequence of the lac operon.
d) is at low concentration when glucose is present.
e) inhibits transcription of the lac operon.
36. You would like to clone a piece of DNA into a plasmid and then use blue/white
selection to identify bacteria containing a plasmid with the DNA insert. You forget to
incubate your plasmid with restriction enzyme before the cloning. What would you
observe on the agar plate the following day?
a) White colonies.
b) No colonies.
c) Blue and white colonies.
d) Blue colonies.
e) Bacteria overgrowing the plate.
37. You would like to clone a piece of DNA into a plasmid and use blue/white selection
to identify bacteria containing a plasmid with an insert. By mistake, you used bacteria
that have the complete lac operon in their genome. What would you observe on the
agar plate the following day?
a) Some blue colonies with plasmids containing the DNA insert.
b) Some white colonies with plasmids containing the DNA insert.
c) Blue and white colonies.
d) Some white colonies containing plasmids without the DNA insert.
e) No colonies.
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38. What would be the effect of replacing the trp codons in the sequence of the
tryptophan operon that codes for the leader peptide with codons for lysine? Compare
with the normal trp operon.
a) Production of full-length trp mRNA would not be dependent upon the trp
concentration.
b) When trp levels were low, higher amounts of full-length mRNA would be
produced.
c) When trp levels were high, higher amounts of full-length mRNA would be
produced.
d) When trp levels were high, lower amounts of full-length mRNA would be
produced.
e) Rho would not be able to bind to the leader mRNA to cause attenuation of
transcription.
39. What happens when tryptophan levels are high in bacteria?
a) Some transcription of the 5’ end of the trp operon occurs.
b) The trp repressor protein is tetramer that contains 4 molecules of trp.
c) The binding of trp decreases the affinity of the trp repressor for the operator.
d) Translation of the leader peptide is terminated.
e) Regions 2 and 3 of the leader mRNA sequence form a stem loop.
40. Which of the following does NOT contribute to the regulation of transcription of the
trp operon?
a) Transcription and translation occur simultaneously in prokaryotes.
b) A leader sequence that codes for a short peptide that contains trp residues.
c) Stem loop formation between different regions of the leader sequence mRNA.
d) The presence of the trp aporepressor protein.
e) A catabolite activating protein binding site upstream of the promoter.
41. Which of the following concerning eukaryotic DNA is correct?
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a) When eukaryotic genomic DNA is centrifuged on a density gradient, satellite
DNA is found in the same band as DNA containing tandemly-repeated genes.
b) Tademly-repeated genes are considered to be non-functional spacer DNA.
c) In a given organism, the DNA nucleotide sequence of individual genes coding for
18S rRNA is highly variable.
d) The property of microsatellites that is exploited in DNA fingerprinting is the
variability in the DNA nucleotide sequence of microsatellites in different
individuals.
e) The A and Ggenes are most susceptible to cleavage by DNases during the fetal
stage of human development.
42. The following shows the ends of a piece of DNA that you would like to amplify using
the polymerase chain reaction. Which of the following are the correct set of primers
that you should choose?
5’ ACC CCC TCC AGA ----------------------------------GGG CCA GCG TAT 3’
3’ TGG GGG AGG TCT --------------------------------- CCC GGT CGC ATA 5’
a) Forward = 5’ ACC CCC TCC AGA 3’, reverse = 5’ATA CGC TGG CCC 3’
b) Forward = 5’ AGA CCT CCC CCA 3’, reverse = 5’ CCC GGT CGC ATA 3’
c) Forward = 5’ TTG GGG AGG TCT 3’, reverse = 5’ TAT GCG ACC GGG 5’
d) Forward = 5’ AAA GGG CCA GCG 3’, reverse = 5’ TTT CGG AAG TCT 3’
e) Forward = 5’ GGG CCA GCG TAT 3’, reverse = 5’ TCT GGA GGG GGT 3’
43. Which of the following is a feature of chromatin?
a) Moderate digestion of chromatin with DNases yields amino acids and
deoxyribonucleotides.
b) Chromatin is found in its most condensed form in mitosis.
c) Histones are the only proteins found in chromatin.
d) A histone 2A and 2B dimer is found in the linker region of chromatin.
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e) DNA that is actively being transcribed exists in cells as heterochromatin.
44. The solenoid structure of chromatin forms when
a) double-stranded DNA forms supercoils.
b) double-stranded DNA wraps around the core histones.
c) nucleosomes form a spiral shape with 6 nucleosomes per spiral.
d) scaffold proteins attach to form a highly condensed form of chromatin.
e) Chromatin is isolated in low (non-physiological) salt conditions.
45. Which of the following would you expect to happen if a mutation was made so that
all of the lysine residues in yeast histones were converted to glycine?
a) The histone acetylase, Gnc5, would not bind to Gnc4.
b) Ume6 would not bind to URS-1.
c) The amount of acetylation on histone would be increased.
d) Transcription of genes controlled by Gnc4 would decrease.
e) Gnc4 would not bind to UAS.
46. Which of the following is NOT a modification that is made to histones?
a) Acetylation of lysine residues.
b) Ubiquitination of lysine residues.
c) Methylation of lysine residues.
d) Acetylation of arginine residues.
e) Phosphorylation of serine or tyrosine residues.
47. Which of the following concerning CG islands is correct?
a) In euchromatin, CG islands are methylated.
b) Sin3 binds to methylated cytidine.
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c) Sin3 binds to acetylases.
d) Histones in the region of Sin3 are acetylated.
e) Transcription is increased in regions with deactylated histones.
48. The purpose of the HIS gene in the “reporter” plasmid of the yeast two-hybrid system
is to
a) ensure that the yeast also have both the fish and the bait plasmid.
b) show that there is an interaction between the DNA binding domain of the “bait”
construct and the activation domain of the “fish” construct.
c) ensure that yeast with the plasmid will live in medium without His.
d) show that there is an interaction between the protein of interest and the protein
expressed by the “fish” construct.
e) show that the yeast with the plasmid will turn blue in the presence of X-gal.
49. Transcription and translation of the “bait” construct will produce
a) a fusion protein of Gal4 with a protein of interest.
b) full-length Gal4 protein.
c) a fusion protein of the Gal4 DNA binding domain and a known protein.
d) a fusion protein of the Gal4 activation domain and an unknown protein.
e) a fusion protein of the Gal4 DNA biding domain and Gal4 activation domain.
50. In the regulation of transcription by glucocorticoids,
a) CBP possesses histone deacetylase activity.
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b) receptors for glucocorticoids bind to the TATA box.
c) glucocorticoids bind to the GRE (glucocorticoid response element).
d) Glucocorticoids increase the transcription of all genes in the cell.
e) receptors for the glucocorticoids bind to hsp90 in the cytoplasm.
51. Which of the following concerning in the regulation of transcription by thyroid
hormones is correct?
a) Thyroid hormones bind to receptors in the cytoplasm.
b) The binding of thyroid hormone to its receptor is required for receptor binding to
DNA.
c) The thyroid hormone receptor is a homodimer.
d) In the absence of thyroid hormone, histone deacetylation is observed.
e) The thyroid hormone receptor without bound thyroid hormone associates with
hsp90.
52. A Northern blot would be performed to determine if a group of cells
a) express RNA with a specific nucleotide sequence.
b) have RNA.
c) have DNA.
d) express a specific protein.
e) have a gene with a specific nucleotide sequence.
The following questions 53 through 75 are based on labs 1 through 6:
53. As a summer job you are working for BIO250 in the lab preparing solutions for the
summer course. You are making up practice gels at a concentration of 0.5% agarose
and you need enough for six gels. Each gel requires 40ml of agarose, so you decide to
make up 250 ml. How much agarose do you need to make 250 ml of a 0.5% solution?
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a) 1.25 g
b) 1.0 g
c) 0.25 g
d) 0.125 g
54. Which of the following statements describes a DIFFERENCE between the structure
of DNA and RNA?
a) The 3′ end of RNA has a hydroxyl group on carbon 3′.
b) In DNA, the nitrogenous bases can be cytosine, uracil, guanine, and adenine.
c) In RNA, the nitrogenous base is attached to carbon 1′.
d) In DNA, these is no hydroxyl group attached to carbon 2′.
55. You wish to amplify some DNA and notice that there is a high content of G and C at
the ends of the sequence. You should increase the temperature in which step of the
polymerase chain reaction?
a) Synthesis.
b) Termination.
c) Denaturation (melting).
d) Annealing.
56. Which is INCORRECT concerning the over-all structure of the B-form DNA?
a) It is the naturally occurring form in tissues.
b) It is a right-handed helix.
c) It is a left-handed helix.
d) It consists of ten base pairs per turn.
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57. Choose the CORRECT statement
a) The Tm (melting temperature) of DNA is decreased with increased salt
conditions.
b) Proteins interact with the base pairs via the major and minor grooves.
c) Ethidium Bromide interacts with the phosphate groups of dsDNA.
d) Covalent bonds between base pairs help to stabilize the dsDNA.
58. Transcription of a 1000bp gene called "SMARTY" gave an mRNA strand that
consisted of 30% U and 40% G. What is the total C and A % in the mRNA?
a) 40%
b) 70%
c) 30%
d) not enough information given.
59. Which of the following is NOT a function of sodium dodecyl sulfate (SDS) in the
isolation of DNA from animal cells?
a) Precipitation of proteins from solution.
b) Denaturation of cellular proteins.
c) Lysis of the plasma membrane.
d) Lysis of the nuclear membrane.
e) Disruption of chromatin structure.
60. Which of the following is NOT CORRECT?
a) Glutamate is an acidic amino acid.
b) Glutamine is a non-polar amino acid.
c) Methionine is hydrophobic and a sulfur containing amino acid.
d) Lysine is a basic amino acid.
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61. The alpha helix is an example of what type of protein structure?
a) Primary.
b) Secondary.
c) Tertiary.
d) Quarternary.
62. Which of the following reagents is NOT used to break down cellular membranes or
cell walls?
a) Lysozyme.
b) NP-40.
c) Potassium acetate.
d) Sodium dodecyl sulphate.
63. A circular chromosome of 8.5 kb is digested with the HINDIII enzyme. Knowing that
HINDIII recognizes and cleaves AAGCTT sequences, how many fragments will you
expect to have from the digestion?
a) 3 fragments.
b) 2 fragments.
c) 1 fragment.
d) More than 3 fragments.
64. What is the role of the restriction buffer when setting up a restriction digest reaction?
The restriction buffer
a) negatively charges DNA fragments to enable their migration during
electrophoresis.
b) denatures the DNA molecules.
c) provides ionic medium necessary for enzyme to be able to function optimally.
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d) makes samples visible when loading the gel.
65. Before the 1970’s the DNA molecule was the most difficult cellular molecule for a
biochemist to analyze. The string of nucleotides that form the genetic material could
only be examined indirectly by protein or RNA sequencing or by genetic analysis.
The discovery of restriction nucleases caused a revolution in the genetic engineering
field. From the following options choose the one/ones that explain the importance
of restriction enzymes (RE) in biotechnology:
a) REs are involved in DNA synthesis; their isolation enabled the development of
the polymerase chain reaction (PCR) technique.
b) REs protect endogenous DNA by methylation, preserving the genetic material.
c) REs cleave RNA molecules, providing an easy way to purify DNA.
d) REs cut the double stranded DNA at specific sites, which result in the ability to
manipulate DNA with precision in a test tube or an organism.
66. What are the most appropriate units in a restriction map?
a) bp
b) kDal
c) S
d) mm
e) micrometer
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67. Which of the following would increase the resolving power of agarose gel
electrophoresis?
a) Higher voltage.
b) Lower current.
c) Higher % agarose gel.
d) Increase ion concentration in running buffer (TAE).
e) Increase ion concentration in agarose gel.
68. On an agarose gel RNA isolated from E. coli is being separated; you notice that 23S
rRNA band is less intense compared to the 16S and 5S rRNA species. What is a
possible reason for this?
a) Since the rRNA species is found at a 1:1:1 ratio, this is a normal observation.
b) RNA degradation has occurred.
c) You shouldn't normally see the 23S rRNA band on a gel since it migrates close to
genomic DNA.
d) There was not enough ethidium bromide in the gel.
69. Potassium acetate is:
a) Insoluble.
b) Used for precipitating out RNA.
c) Used for precipitating out proteins and large DNA associated with SDS.
d) Used for lysing bacterial cells.
70. Why is the 16S rDNA sequence analyzed (using BLAST) to identify unknown
bacteria?
a) The 16S rRNA gene is rarely found in bacteria species.
b) The 16S rRNA gene is fairly generic in various species of bacteria.
c) The 16S rRNA gene is the least abundant coding sequence in bacteria.
d) The 16S rRNA gene has a significant number of variable regions in bacteria
species.
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71. The addition of dideoxynucleotides (ddNTP) prevents further polymerization because
ddNTP’s,
a) are radioactive and unstable.
b) lack oxygen on the 3’ carbon.
c) lack a phosphate group on the 5’ carbon.
d) are bulky and are not able to bind to other nucleotides.
72. The BLAST search tool can be used:
a) To construct evolutionary relationships among species.
b) To identify conserved and variable regions of a set of sequences.
c) To determine if a sequence codes for an enzyme.
d) To find proteins that interact with a DNA sequence in vivo.
73. Which of the following information is not found in a Genbank record?
a) Accession number.
b) Bit score.
c) Organism name.
d) Reference.
74. Which tool would you use to compare two hormones, each from separate species,
which are believed to perform the same function?
a) BLAST.
b) ClustalW.
c) Genbank.
d) Pub Med.
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75. Which of the following electrophoresis gels accurately represents the way in which
the given DNA fragments would run on the gel?
I)
5' - A - C - 3'
II)
5' - A - C - T - G - T - 3'
III) 5' - A - C - T - 3'
IV) 5' - A - C - T - G - 3'in which the given DNA fragments would run on the
gel?
I) 5' - A - C -
3'
IV) 5' - A - C - T - G - 3'
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