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Q:
Most eukaryotic RNA consists of coding regions, called ____, and noncoding regions, called ____.
a. introns; exons
b. exons; introns
c. spliceons; codons
d. codons; spliceons
e. introns; codons
Q:
Transcription of a typical gene encoding a polypeptide in eukaryotes involves all of the following EXCEPT:
a. the splicing together of a number of exons in the DNA prior to transcription.
b. synthesis by RNA polymerase II.
c. transcription of DNA corresponding to both introns and exons.
d. transcription of the DNA which encodes the N-terminal of the polypeptide prior to DNA encoding to the C-terminal.
e. addition of the poly(A)+ tail.
Q:
All are true for translation in eukaryotic cells EXCEPT:
a. transcription and translation are spatially separated.
b. mRNAs are monocistronic.
c. transcription occurs in the nucleus.
d. primary transcripts undergo processing to mature mRNAs.
e. all are true.
Q:
The structural motif found in a number of transcriptional factors which is not a DNA-binding domain, but rather is associated with protein-protein interactions is:
a. a leucine zipper.
b. a zinc finger.
c. a helix-turn-helix.
d. an enhancer element.
e. all of the above.
Q:
The leucine zipper is a protein motif held together by:
a. H-bonds.
b. hydrophobic interactions.
c. ionic interactions.
d. metal ion binding.
e. protein:DNA interactions.
Q:
Characteristics of the Zn-finger motif include all EXCEPT:
a. repeated motif in DNA-binding proteins.
b. 2 Cys and 2 Met coordinate the Zn.
c. binds the major groove of DNA.
d. interacts with about five nucleotides/ Zn-finger.
e. all are true.
Q:
Lacrepressor is an example of the DNA-binding motif common to many prokaryotic regulatory proteins and is:
a. a homeobox.
b. a zinc finger.
c. a basic region-leucine finger.
d. a helix-turn-helix.
e. none of the above.
Q:
The base-pair edges in the ____ groove act as a(n) ____ identifiable through ____ with specific proteins.
a. minor; enhancer; H-bonding
b. minor; recognition matrix; H-bonding
c. major; recognition matrix; H-bonding
d. major; repressor; ionic binding
e. major; transcriptional silencer; ionic bonding
Q:
All are true for homeobox domains EXCEPT:
a. typically comprise about 90% of the protein mass.
b. found in virtually every eukaryote.
c. act as sequence-specific transcriptional factors.
d. contain helix-turn-helix motifs.
e. all are true.
Q:
The recurring structural feature in DNA-binding proteins is the presence of ____ segments that fit into the ____ grove of B-DNA.
Q:
All are components of the basic rule of macromolecular recognition EXCEPT:
a. protein recognizes nucleotide sequences by atomic contacts with bases and sugar-phosphate backbone usually in the major groove.
b. protein contacts involve H-bonds and salt bridges with electronegative oxygens of the phosphodiester linkages.
c. proteins present a three-dimensional shape or contour structurally and chemically complementary to the surface of the DNA sequence.
d. numerous atomic interactions underlie recognition and binding.
e. all are components.
Q:
Huge multi-subunit entities that mediate ATP-dependent conformational changes that peel 50bp of DNA from the edge of nucleosome core particles and create a "bulge" in the DNA:core nucleosomes association are called:
a. histone deacetylase complexes (HDACs).
b. DNA-bound transcriptional activators.
c. chromatin-remodeling complexes .
d. general transcriptional factors (GTFs).
e. all are true.
Q:
Enzymes that acetylate the group of lysine in the histidine tails are called ____ and are involved in ____.a. histone deacetylases; restoring chromatin to a repressed stateb. histone acetyltransferases (HATs); initial events in transcriptional activationc. histone activases; formation of the de-repression complexd. Schiff base formation; promoting the formation of closed complexese. none of the above
Q:
The eukaryotic transcription factor that exhibits a sequence specificity for the TATA box is:
a. TFIIB.
b. TFIIC.
c. TFIID/TBP.
d. RNA polymerase II.
e. TFIIH.
Q:
The metallothionein gene promoter consists of all EXCEPT:
a. TATA box.
b. GC box.
c. glucocorticoids response element (GRE).
d. heat shock element (HSE).
e. all are true.
Q:
Heat shock element (HSE) is a(n) ____ found in the ____ region of genes whose transcription is activated in response to ____.
a. silencer; enhancer; cold
b. response element; promoter; elevated temperature
c. promoter; enhancer; elevated temperature
d. enhancer; response element; elevated temperature
e. silencer; promoter; cold
Q:
All are correct about enhancer sequences in eukaryotic cells EXCEPT:
a. they can occur either upstream or downstream of the gene.
b. they can be in either orientation (bi-directional).
c. enhancer function is dependent on recognition by a specific transcription factor.
d. specific transcription factor binding at an enhancer stimulates transcription by interacting with RNA polymerase II.
e. all are correct.
Q:
All may be RNA polymerase II promoter constituents EXCEPT:
a. the core element where general transcription factors (GTFs) bind.
b. where enhancers bind transcriptional activators.
c. where silencers bind repressors.
d. a TATA box indicating the transcription start site.
e. all can be constituents.
Q:
The heptapeptide repeat in the carboxy terminal domain (CTD) in the RPB1 subunit of RNA polymerase II is phosphorylated to ____.
a. convert to an elongation complex
b. bind to DNA
c. form a holo-RNA polymerase II
d. initiate transcription
e. activate termination
Q:
Which of the following is true of TATA boxes?
a. they are found within the core sequence of a gene regulatory sequence
b. they are found downstream of the gene being transcribed
c. they represent an area of DNA more easily opened than other areas
d. a and c are true
e. a, b, and c are true
Q:
The DNA-binding proteins that recognize and accurately initiate transcription at specific eukaryotic promoter sequences are called:
a. Enhancers.
b. transcription factors.
c. response elements.
d. chromatin-remodeling complexes.
e. all are true.
Q:
Transcription in eukaryotic cells which is resistant to ï¡-amanitin is carried out by RNA polymerase:
a. I only.
b. II only.
c. III only.
d. I and III.
e. I, II and III.
Q:
RNA polymerase II:
a. is located in the nucleolus and transcribes the major ribosomal RNA genes.
b. is located in the nucleoplasm and transcribes the protein-encoding genes through mRNAs.
c. transcribes the 5S RNA genes.
d. transcribes RNA genes associated with tRNA processing.
e. transcribes tRNA genes and protein transport genes.
Q:
All are true for transcription activation EXCEPT:
a. takes place when a transcriptional activator protein bound to DNA makes protein : protein contacts with RNA polymerase.
b. the degree of transcriptional activation is proportional to the strength of the protein : protein interaction.
c. a nucleotide sequence binding site for a DNA-binding protein serves as an activator site if DNA-binding protein can interact with promoter-bound RNA polymerase.
d. if the DNA-bound transcriptional activator makes contact with two different components of RNA polymerase, the transcription is markedly elevated.
e. all are true.
Q:
All of the following are control mechanisms that regulate transcription in prokaryotes EXCEPT:
a. protein : protein interactions
b. DNA : protein interactions
c. RNA : protein interactions
d. a and b
e. a, b, and c
Q:
When the cellular level of tryptophan decreasesin E. coli:
a. tryptophan-bound Trp repressor associates with trp operator.
b. Trp aporepressor has lowered affinity for trp promoter allowing RNA. polymerase binding and transcription of the trp operon.
c. tryptophan binds trp inducer to promote positive control of trp promoter.
d. trp repressor has a greater affinity for trp operator.
e. none of the above.
Q:
Which of the following is not a component of the araBADoperon?
a. araA, encodes L-arabinose isomerase
b. araK, encodes L-arabinose kinase
c. araD, encodes ribulose-5-phosphate epimerase
d. araC, encodes a regulatory protein that acts as both a repressor and activator
e. araI, the promoter for the operon
Q:
All are characteristics of catabolic activator protein (CAP) EXCEPT:
a. ensures that the operons necessary for metabolism for alternate energy sources remains repressed until the supply of glucose is exhausted.
b. overrides the influence of any inducer that might be present.
c. cAMP enhances CAP's affinity for DNA.
d. N-terminal end binds cAMP and C-terminal end binds DNA.
e. all are true.
Q:
Which of the following is true of the lacoperon?
a. it is negatively controlled via the lac repressor, a protein that only binds to DNA in the absence of lactose
b. it is positively controlled via CAP, a protein that is activated by binding to ATP
c. lactose represses the lac operon but this repression can be removed by addition of IPTG
d. binding of lactose (or an analog of lactose) increases the affinity of the lac repressor for DNA
e. none of the above
Q:
All are lacrepressor properties EXCEPT:
a. tetrameric protein expressed constitutively.
b. binding site for DNA.
c. binding site for mRNA.
d. binding site for inducer.
e. blocks elongation so initiation is aborted.
Q:
All are components of the lacoperon EXCEPT:
a. the structural genes for lacZ, lacY and lacA.
b. the operator and promoter sequences.
c. lacI gene.
d. promoter for the lacI gene.
e. all are correct.
Q:
Expression of genes independently of regulation is termed:
a. negative regulation.
b. constitutive expression.
c. transcription expression.
d. repressible regulation.
e. autoregulation.
Q:
In prokaryotes, gene expression is often responsive to small molecules where increasing synthesis of enzymes for metabolism of a certain substrate is termed ____ and the substrate is called ____. Likewise metabolic products that decrease synthesis of enzymes for their production are called ____ and carry out ____.
a. autoregulation; regulatory; co-repressors; initiation
b. co-induction; induction; co-repressors; initiation
c. induction; co-inducer; co-repressors; repression
d. induction; co-inducer; repressor; co-repression
e. all are true
Q:
Operons are a(n) ____ sequence lying adjacent to the DNA being transcribed and are composed of a promoter located next to a(n) ____ that interacts and is controlled by a(n) ____ protein.
a. initiation; operator; repression
b. operator; repressor; regulatory
c. regulatory; repressor; activator
d. regulatory; operator; regulatory
e. none are true
Q:
In bacteria, single polycistronic mRNA encodes for:
a. a single enzyme although there are many in the metabolic pathway.
b. multiple enzymes of the particular pathway.
c. a single mRNA which is split into multiple mRNAs before translation.
d. a single peptide with multiple catabolic sites.
e. none of the above.
Q:
Characteristics of rho factor include all EXCEPT that it:a. recognizes and binds C-rich regions of RNA transcripts.b. binding regions must be ribosome free.c. advances in the 5'->3' direction to the transcription bubble.d. unwinds transcript and template to free nascent RNA.e. all are true.
Q:
One of the termination mechanisms in bacteria utilizes the ____ factor that is an ATP-dependent helicase.
Q:
Intrinsic RNA chain termination is determined by specific sequences in the DNA called ____ sites.
a. termination
b. rho binding
c. template binding
d. supercoil
e. all are true
Q:
Transcription chain elongation is thought to generate ____ supercoils ahead of the transcription bubble and _____ supercoils behind it.
a. positive; negative
b. negative; positive
c. negative; negative
d. positive; positive
e. none of the above
Q:
The initiation site binds a ____ nucleotide base pairing with the ____ base exposed within the ____ promoter complex, and then the second base is added to the ____ of the first base.a. pyrimidine; -1; closed; 3'-Ob. pyrimidine; +1; closed; 5'-Oc. purine; +2; closed; 3'-Od. purine; -1; open; 5'-Oe. purine; +1; open; 3'-O
Q:
In order for transcription to begin, the DNA-duplex must be "opened" to allow RNA polymerase access to single stranded template. All facilitate "opening" of DNA-duplex EXCEPT:a. low melting temperature, Tm, in the Pribnow box.b. A:T rich DNA duplex.c. negative supercoiling.d. binding of RNA polymerase -subunit.e. all are true.
Q:
All are true for the prokaryotic promoter for the rrngene in E. coliEXCEPT that it:a. encodes for rRNA.b. has a -10 region Pribnow box.c. has a -35 region consensus sequence.d. has an upstream (UP) element at -55.e. all are true.
Q:
Within the ____ are two consensus sequence elements, the ____ near ï€10 with a sequence of TATAAT, and the ____ containing the consensus TTGACA.a. termination sequence; rho subunit; sigma subb. termination sequence; Pribnow box; sigma subunit unitc. promoter sequence; rho subunit; Pribnow boxd. promoter sequence; Pribnow box; -35 regione. promoter sequence; rho subunit; -35 region
Q:
Nucleotides in the "plus" direction are said to lie ____ the transcription start site.
a. downstrand of
b. upstream of
c. downstream of
d. upstrand of
e. positive to
Q:
The base in DNA that specifies the first base in the RNA transcript is called a(n) ____ and is numbered ____.a. promoter; -5b. enhancer; -35c. transcription start site; 0d. transcription start site; +1e. promoter complex; +5
Q:
Treatment of the RNA polymerase/DNA complex with DNase in vitrois a DNA footprinting technique used to:
a. identify the termination sequence for transcription.
b. locate the start site for transcription.
c. locate the promoter site.
d. identify the position of enhancer sequences.
e. none of the above.
Q:
All are stages in transcription EXCEPT:
a. binding of RNA polymerase holoenzyme at the promoter sites.
b. chain elongation.
c. DNase I activity on RNA polymerase/DNA complex.
d. initiation of polymerization.
e. chain termination.
Q:
Nucleotide sequences that identify the location of transcription start sites and regulate the level of transcription are called:
a. sigma factors.
b. Pribnow boxes.
c. TATA boxes.
d. promoters.
e. enhancers.
Q:
The subunit in E. coliRNA polymerase which is required for recognition of the promoter sequence is:
Q:
All are factors or subunits contained within the E. coliRNA polymerase holoenzyme in prokaryotic organisms EXCEPT:
Q:
The ____ strand has the same nucleotide sequence and direction as that of the RNA transcript, with the ____ end of mRNA encoding the N-terminus of the protein.
a. template; 3'
b. template; 5'
c. nontemplate; 3'
d. nontemplate; 5'
e. lagging; 5'
Q:
The stand of dsDNA that is read by RNA polymerase is termed the ____ strand with RNA polymerase moving ____ along it. The polymerase forms a ____, growing in the ____ direction.
Q:
Both prokaryotes and differentiated eukaryotic cells express ____ of their genes at any given time in the process called ____.
a. a small number; transcription
b. a small number; translation
c. a large number; transcription
d. all; translation
e. all; transcription
Q:
Which of the following DNA repair mechanisms is correctly defined?
a. mismatch repair system: corrects errors created from chemical modification of DNA
b. photolyase: repairs cyclobutane dimers formed between adjacent cytosine residues
c. base excision repair: uses DNA glycosylase to remove a damaged base by cleaving the glycosidic bond
d. nucleotide excision repair: removes a single nucleotide by cutting the phosphodiester backbone
e. none of the above
Q:
Which of the following activities is NOT associated with the DNA polymerase III holoenzyme?a. 3-exonucleaseb. 5-exonucleasec. sliding clampd. removal of single stranded binding proteinse. all are activities of the holoenzyme
Q:
Which of the following would most likely cause a frameshift mutation?
a. an alkylating agent such as methyl iodide
b. a base analog such as 5-bromouracil
c. a chemical mutagen such as nitrous acid
d. an intercalation agent such as acridine orange
e. none of the above
Q:
Which of the following statements explains why the adenine analog, 2-aminopurine (2-AP), can cause mutations in DNA when it is inserted in place of a site normally occupied by A?
a. 2-AP forms 2 hydrogen bonds with thymine
b. 2-AP undergoes oxidative deaminiation to hypoxanthine which basepairs with C
c. 2-AP can form a single hydrogen bond with C
d. 2-AP is often found as a schiff base that crosslinks with T
e. none of the above
Q:
Which of the following statements explains why the thymine analog, 5-bromouracil (5-BU), can cause mutations in DNA when it is inserted in place of a site normally occupied by T?
a. the bromine of 5-BU is similar in size to the methyl group of T and thus pairs with A
b. 5-BU is often found as the enol tautomer that hydrogens more effectively with G than with A
c. the bromine is subject to nucleophilic attack by a methyl transferase resulting in newly synthesized DNA being recognized as the methylated parent strand
d. the 5-BU is subject to removal resulting in a frame-shift mutation
e. none of the above
Q:
____ provides a mechanism for generating a variety of protein isoforms of immunoglobulins from a limited number of genes.
a. Genetic recombination
b. Replication licensing
c. DNA polymerase
d. DNA rearrangement
e. All are true
Q:
The vast diversity of immunoglobulin sequences is explained by:
a. DNA rearrangement
b. large sections of DNA devoted to immunoglobulin formation
c. susceptibility of the immunoglobulin genes to mutation
d. sensitivity of formed immunoglobulin proteins to environmental factors
e. all of the above
Q:
The region of immunoglobulins that form the structural site complementary to some part of an antigen's structure are:
a. immunoglobulin fold region.
b. hinge region.
c. constant heavy region.
d. hypervariable region.
e. all are true.
Q:
B-cells, T-cells, and macrophages are cell types capable of ____ as a mechanism of producing ____ essential to the immune response.
a. replication rearrangement; antibodies
b. complimentarity modification; antigens
c. DNA replication; genes
d. DNA rearrangement; antibodies
e. All are true
Q:
What type of mutation most likely results from the alkylation of the oxygen on position 6 of guanine base producing O6-methylguanine?
a. deletion
b. insertion
c. transition
d. transversion
e. frameshift
Q:
Nitrous acid causes the oxidative deamination of cytosine producing uracil. What point mutation is the logical result?
a. C-G to A-T, only
b. C-G to T-A, only
c. C-G to G-C, only
d. both a and b are correct
e. a, b and c are correct
Q:
Misincorporation of all subsequent amino acids results from ____ mutations.
a. chemical
b. base shift
c. frameshift
d. transition
e. all are true
Q:
When the thymine analog, 5-bromouracil, incorporates into DNA normally occupied by thymine, what type of mutation can occur?
a. T-A to A-T, only.
b. T-A to C-G, only.
c. C-G to T-A, only.
d. both b and c are correct.
e. a, b, and c are correct.
Q:
Mutations in DNA may result from all of the following EXCEPT:
a. spontaneous mutations due to errors in replication.
b. physical insults on the cell, such as UV light.
c. errors in transcription.
d. chemical mutagens.
e. introduction of a base analog into DNA.
Q:
The exchange of one base for another is called a ____, while insertions and deletions are referred to as ____.
a. frameshift mutation; transition mutations
b. frameshift mutation; point mutations
c. point mutation; transversion mutations
d. point mutation; frameshift mutations
e. transition mutation; transversion mutations
Q:
A transversion mutation would be replacing T by:
a. A.
b. C.
c. U.
d. G.
e. either A or G.
Q:
A transition mutation would be replacing A by:
a. T.
b. C.
c. U.
d. G.
e. either T or C
Q:
Together with ____, ____ provide(s) for genetic variability within species and, ultimately, the evolution of new species.
a. DNA repair; DNA glycosylase
b. DNA glycosylase; recombination
c. recombination; mutations
d. mutations; DNA glycosylase
e. DNA repair; mutations
Q:
All are characteristics of mammalian nucleotide excision repair EXCEPT:
a. sugar-phosphate backbone is cut in two places
b. the region of DNA excised is generally 27-29 bases in length
c. resulting gap is filled in by DNA polymerase ï¢
d. DNA backbone is closed with DNA ligase
e. all are true
Q:
In base-excision repair, the first enzyme in the sequence is ____ creating a(n) ____ site.
a. DNA polymerase III; ligase binding
b. DNA glycosylase; apurinic or apyrimidinic
c. DNA polymerase I; apurinic or apyrimidinic
d. DNA ligase; polymerase III binding
e. AP endonuclease; ligase binding
Q:
The repair of cyclobutane pyrimidine dimers involves bacterial ____ and the cofactors ____ and ____.
a. DNA methylase; S-adenosyl methionine; ATP
b. DNA carboxylase; CoA; CoQ
c. DNA polymerase I; flavin; TPP
d. photolyase; flavin; NADH
e. photolyase; flavin; pterin
Q:
____ promotes the formation of covalent bonds between ____ thymine residues in a DNA strand creating a ____ ring called a thymidine dimer.
a. Visible light; adjacent; cyclohexyl
b. Visible light; nearby; cyclobutyl
c. UV light; adjacent; cyclobutyl
d. UV light; nearby; cyclohexyl
e. IR light; adjacent; cyclobutyl
Q:
When the methyl-directed repair system detects a mismatch in dsDNA it:
a. corrects the DNA strand that is methylated by removal of a single base and replacing with the correct one
b. corrects the DNA strand that is methylated by removal of a sting of nucleotides and replacing with correctly matched nucleotides
c. corrects the DNA strand that is not methylated by removal of a single base and replacing with the correct one
d. corrects the DNA strand that is not methylated by removal of a sting of nucleotides and replacing with correctly matched nucleotides
e. none of the above.
Q:
All are common forms of DNA damage EXCEPT:
a. replication errors resulting in a missing or incorrect base.
b. bulges due to deletions or insertions.
c. UV-induced base alterations, such as pyrimidine dimers.
d. strand breaks at phosphodiester bonds or within deoxyribose rings.
e. all of the above.
Q:
Mutations in BACA1 and BACA2 genes causes increased likelihood of ____ because BACA1 protein functions in regulation of the cell cycle in response to ____, and BACA2 protein participates in DNA repair by ____.
a. breast and ovarian cancer; DNA damage control; homologous recombination
b. breast and ovarian cancer; homologous recombination; DNA damage control
c. uterine cancer; transposition; homologous recombination
d. genetic recombination; transposition; homologous recombination
e. none are true
Q:
All are characteristics of transposons EXCEPT:
a. segments of DNA moved non-enzymatically in the genome.
b. unstable location within genome.
c. range in size from hundreds of bps to 8 kbp.
d. the smallest transposons are called insertion sequences.
e. a major force in evolution.
Q:
RuvA, RuvB, and RuvC are involved in all EXCEPT:
a. processing Holliday junctions into recombination products.
b. aiding strand invasions of the 3'-ssDNA into homologous DNA duplexes.
c. Holliday junction-specific helicase complex.
d. dissociates the RecA filament and catalyzes branch migration.
e. all are true.