Questions from All Exams and Quizzes Flashcards
Which of the following are NOT characteristics of a DNA double helix?
a. nitrogenous bases on the inside of the helix
b. strands antiparallel
c. 25 bases per one turn of the helix
d. A-T base pairs contain two hydrogen bonds, C-G base pairs contain 3 hydrogen bonds
c. 25 bases per one turn of the helix
How do purines and pyrimidines differ?
a. pyrimidines have a double ring while purines have a single ring structure
b. purines are the components of RNA; pyrimidines are only found in DNA
c. purines have double ring while pyrimidines have a sing ring structure
d. pyrimidines are only found in RNA; purines are the components of DNA
c. Purines have the double ring while pyrimidines have a single ring structure
Which of the following statements about the major groove of double stranded DNA is true?
a. It is narrower than the minor groove.
b. It refers to the space between the sugar and the phosphate on the DNA backbone.
c. It allows proteins to ‘read’ the DNA sequence without disrupting the double helix.
d. All of the statements are correct.
e. None of the statements are correct
c. It allows proteins to ‘read’ the DNA sequence without disrupting the double helix
One function of DNA pol I during replication in prokaryotes is to:
a. join the ends of adjacent Okazaki fragments together
b. separate the double-stranded DNA into single-stranded regions
c. replicate the lagging strand of DNA in eukaryotic cells
d. relieve tension induced by supercoiling
e. remove the RNA primers that initiate replication
e. Remove the RNA primers that initiate replication
Which of the following is NOT a property of DNA polymerase III?
a. It is responsible for incorporating most of the nucleotides in the leading strand.
b. It contains a 3’ to 5’ proofreading activity.
c. It is responsible for incorporating most of the nucleotides in the lagging strand.
d. It does not require primers to extend the leading strand.
e. It has a very low error rate.
d. It does not require primers to extend the leading strand
If the sequence GTGAT mutates to become GTAAT, the G to A alteration is called a:
a. depurination
b. transversion
c. transition
d. tautomeric shift
c. Transition
Which of the following is NOT a step in the repair of a deaminated cytosine?
a. N-glycosylase to remove the damages base
b. primase to synthesize an RNA primer
c. apyrimidinic endonuclease to nick the backbone at the damaged base
d. DNA polymerase to add the correct base
e. DNA ligase to seal the nick in the backbone
b. Primase to synthesize an RNA primer
Site-directed mutagenesis:
a. can be used to produce a specific allele of a gene
b. can be used to modify the function of a gene
c. can be used to modify the binding site for a repressor in the 5’ untranslated region of a gene
d. can be used to restore a mutant gene back to wild-type sequence
e. all of the above
e. All of the above
Restriction enzymes usually only cut foreign viral DNA and ignore their own bacterial DNA. The
reason for this behavior is:
a. their bacterial DNA is methylated
b. transcriptional repression of the restriction enzyme’s structural gene
c. translational modification of the restriction enzyme
d. the heterochromatin state of the bacterial DNA
e. the foreign viral DNA is methylated
a. Their bacterial DNA is methylated
The enzyme used in PCR is:
a. DNA ligase
b. a thermostable DNA polymerase
c. reverse transcriptase
d. the restriction endonuclease PvuII
e. the single-stranded binding protein PCNA
b. A thermostable DNA polymerase
A tautomeric shift during replication can cause the following type of mutation: True / False 11. missense mutation True / False 12. repeat tract expansion True / False 13. silent mutation True / False 14. frameshift mutation True / False 15. neutral mutation
True 11. missense mutation False 12. repeat tract expansion True 13. silent mutation False 14. frameshift mutation True 15. neutral mutation
Which of the following statements about RNA and DNA are true and which are false?
True / False 16. RNA contains ribose rather than deoxyribose sugars
True / False 17. DNA secondary structure is less variable than RNA
True / False 18. RNA polymers incorporate uracil
True / False 19. RNA has a –OH group on the 2’ carbon that DNA lacks
True / False 20. RNA cannot serve as the genetic information storage medium
True 16. RNA contains ribose rather than deoxyribose sugars
True 17. DNA secondary structure is less variable than RNA
True 18. RNA polymers incorporate uracil
True 19. RNA has a –OH group on the 2’ carbon that DNA lacks
False 20. RNA cannot serve as the genetic information storage medium
The function of topoisomerases during replication is to:
True / False 21. join the ends of adjacent Okazaki fragments together
True / False 22. separate the DNA strands from each other
True / False 23. relieve tension induced by supercoiling
True / False 24. remove the RNA primers that initiate replication
True / False 25. generate the primer used to initiate synthesis
The function of topoisomerases during replication is to:
False 21. join the ends of adjacent Okazaki fragments together
False 22. separate the DNA strands from each other
True 23. relieve tension induced by supercoiling
False 24. remove the RNA primers that initiate replication
False 25. generate the primer used to initiate synthesis
Which repair mechanism acts on an apurinic site?
Base excision repair
Which repair mechanism acts on a thymine dimer?
Nucleotide excision repair OR Photolyase
Which repair mechanism acts on a T:C base pair in interphase?
Mismatch repair OR DNA Proofreading
Which repair mechanism acts on a double-stranded break?
Recombinational repair
Which repair mechanism acts on an A:G base pair during DNA synthesis?
DNA Proofreading
Which statement about DNA polymerase III is FALSE?
a. It is responsible for incorporating most of the nucleotides in the leading strand.
b. It contains a 3’ to 5’ proofreading activity.
c. It is responsible for incorporating most of the nucleotides in the lagging strand.
d. It does not require primers to extend the leading strand.
e. It has a very low error rate.
d. It does not require primers to extend the leading strand
One function of DNA pol I during replication in prokaryotes is to:
a. join the ends of adjacent Okazaki fragments together
b. separate the double-stranded DNA into single-stranded regions
c. replicate the lagging strand of DNA in eukaryotic cells
d. relieve tension induced by supercoiling
e. remove the RNA primers that initiate replication
e. Remove the RNA primers that initiate replication
The enzyme used in making cDNA is:
a. DNA ligase
b. a thermostable DNA polymerase
c. reverse transcriptase
d. polynucleotide kinase
e. the single-stranded binding protein PCNA
c. Reverse transcriptase
7-methyl-guanosine is added to mRNA molecules during a processing reaction in eukaryotes. The
unique processing event is a:
a. 3’-5’ triphosphate linkage at the 3’ end of the RNA
b. 2’-5’ triphosphate linkage at the 5’ end of the RNA
c. 3’-5’ triphosphate linkage at the 5’ end of the RNA
d. 3’-2’ triphosphate linkage at the 3’ end of the RNA
e. 5’-5’ triphosphate linkage at the 5’ end of the RNA
e. 5’-5’ triphosphate linkage at the 5’ end of the RNA
The reduced expression of the lac operon in the presence of glucose is an example of :
a. transcriptional activation
b. catabolite repression
c. operon silencing
d. regulatory dominance
e. anabolic repression
b. Catabolite repression
Attenuation at the trp operon in E. coli occurs when:
a. translation and transcription become uncoupled
b. high tryptophan levels inhibit the binding of a repressor protein
c. low tryptophan levels increase the rate of RNA polymerase progression
d. high tryptophan levels allow the formation of a terminator stem-loop in the trpL mRNA
e. the tryptophan membrane transporter increases the rate of tryptophan import
d. High tryptophan levels allow the formation of a terminator stem-loop in the trpL mRNA
Which is most commonly found in the P site of ribosomes?
a. a tRNA with the growing peptide chain attached
b. a tRNA with no amino acid attached
c. a tRNA with a single amino acid attached
d. ribosome releasing factor
e. termination factor
a. A tRNA with the growing peptide chain attached
Which statement about the Shine-Delgarno sequence is FALSE?
a. it is found near the 5’ end of prokaryotic mRNAs.
b. it is complementary to a sequence near the 3’ end of the 16S rRNA.
c. it helps position the small ribosomal subunit near the translation start site.
d. it contains the AUG initiator codon.
e. it is required for efficient translation.
d. It contains the AUG initiator codon
Which of the following methods would be used to determine the amino acid sequence of a peptide?
a. polymerase chain reaction
b. western blotting
c. organism cloning
d. gel shift assay
e. mass spectrometry
e. Mass spectrometry
Mass spectrometry can detect all of these EXCEPT:
a. proteins that have been post-translationally modified.
b. proteins made from mRNAs that have been alternatively spliced.
c. proteins made from mRNAs that have used alternate polyadenylation sites.
d. proteins present in cancer cells but not in normal cells.
e. proteins that have been localized in the wrong cellular compartment.
e. Proteins that have been localized in the wrong cellular compartment.
Which of the following types of mutation is likely to have the greatest consequence to the cell?
a. a G => A change that creates a stop codon within a gene
b. trisomy of an autosome
c. an insertion of a T in a homopolymeric run of Ts
d. an inversion of the long arm of the X chromosome
e. a reciprocal translocation between two autosomes
b. Trisomy of a autosome
A scientist suspects that a short translocation has occurred that might involve a gene that she is
studying. What is the fastest way to determine if the cells carry the translocation?
a. sequence the genome with DNA from the cells
b. use PCR to amplify the gene
c. use a labeled probe of the gene to do in situ hybridization
d. do a chromosome walk with the gene as an initial probe
e. construct a YAC library from the cell’s DNA
c. Use a labeled probe of the gene to do in situ hybridization
Which statement about RNA interference is FALSE?
a. it occurs only in plants.
b. it involves short RNAs that are complementary to the target mRNA.
c. it can inhibit the transcription of the target mRNA.
d. it can cause the degradation of the target mRNA.
e. it can inhibit the translation of the target mRNA.
a. It occurs only in plants
The function of helicases during replication is to:
True / False 14. join the ends of adjacent Okazaki fragments together
True / False 15. separate the DNA strands from each other
True / False 16. relieve tension induced by supercoiling
True / False 17. remove the RNA primers that initiate replication
False 14. join the ends of adjacent Okazaki fragments together
True 15. separate the DNA strands from each other
False 16. relieve tension induced by supercoiling
False 17. remove the RNA primers that initiate replication
Microarrays are useful when studying the gene expression in cancer cells because:
True / False 18. they can identify all of the genes that are overexpressed.
True / False 19. they can identify all of the genes that are underexpressed.
True / False 20. they can identify all of the genes that have point mutations.
True 18. they can identify all of the genes that are overexpressed.
True 19. they can identify all of the genes that are underexpressed.
False 20. they can identify all of the genes that have point mutations.
In partially diploid E. coli cells with the genotype F’ i+ o- z- y+ a-/ chromosome i- o+ z+ y- a+, which
functional gene product(s) would be expressed at high level in the absence of lactose?
True / False 27. β-galactosidase only
True / False 28. β-galactosidase, permease, and transacetylase
True / False 29. permease only
True / False 30. permease and transacetylase
False 27. β-galactosidase only
False 28. β-galactosidase, permease, and transacetylase
True 29. permease only
False 30. permease and transacetylase
Which of the following statements about nucleotides are true and which are false?
True / False 31. The phosphate group is attached to the nitrogenous base.
True / False 32. A nucleotide contains a base, a sugar, and a phosphate group.
True / False 33. The sugar contains two nitrogen atoms.
True / False 34. The nitrogenous base is attached to the sugar by a glycosidic bond.
False 31. The phosphate group is attached to the nitrogenous base.
True 32. A nucleotide contains a base, a sugar, and a phosphate group.
False 33. The sugar contains two nitrogen atoms.
True 34. The nitrogenous base is attached to the sugar by a glycosidic bond.
Histone acetyltransferases act to:
True / False 35. eliminate the positive charge of lysines in histones
True / False 36. increase the compaction of DNA around histones
True / False 37. help the histones reassemble following DNA replication
True / False 38. prevent the translation of histone mRNA molecules
True / False 39. remove covalent modifications on the lysine residues of histones
True 35. eliminate the positive charge of lysines in histones
False 36. increase the compaction of DNA around histones
False 37. help the histones reassemble following DNA replication
False 38. prevent the translation of histone mRNA molecules
False 39. remove covalent modifications on the lysine residues of histones
During protein synthesis, the tRNA synthetase acts to:
True / False 40. attach an amino acid to the anticodon of the tRNA
True / False 41. transcribe the genes encoding tRNAs to produce tRNA molecules
True / False 42. serve as the first initiation factor during ribosome assembly
True / False 43. covalently bind an amino acid to the acceptor stem of the tRNA
True / False 44. cause precursor tRNA molecules to adopt their proper final structure
False 40. attach an amino acid to the anticodon of the tRNA
False 41. transcribe the genes encoding tRNAs to produce tRNA molecules
False 42. serve as the first initiation factor during ribosome assembly
True 43. covalently bind an amino acid to the acceptor stem of the tRNA
False 44. cause precursor tRNA molecules to adopt their proper final structure
The following are tRNA binding sites found within ribosomes: True / False 45. peptidyl site True / False 46. exit site True / False 47. elongation site True / False 48. aminoacyl site
True 45. peptidyl site
True 46. exit site
False 47. elongation site
True 48. aminoacyl site
For which of the following experiments would a DNA microarray be useful?
True / False 49. identifying the binding site for a transcription factor
True / False 50. determining which genes are induced when a chemical is added to a cell’s growth medium
True / False 51. determining which genes are down-regulated in response to heat shock
True / False 52. identifying the site of a DNA inversion
True / False 53. distinguishing between two closely related bacterial subspecies
True 49. identifying the binding site for a transcription factor
True 50. determining which genes are induced when a chemical is added to a cell’s growth medium
True 51. determining which genes are down-regulated in response to heat shock
False 52. identifying the site of a DNA inversion
True 53. distinguishing between two closely related bacterial subspecies