Biochem ch 29

mikebewo's version from 2015-05-20 09:11


Question Answer
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
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'
All are factors or subunits contained within the E. coli RNA polymerase holoenzyme in prokaryotic organisms EXCEPT:
a. ρ (rho).
b. α (alpha).
c. β (beta).
d. β′ (beta prime).
e. σ (sigma).
Treatment of the RNA polymerase/DNA complex with DNase in vitro is 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.
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
All are true for the prokaryotic promoter for the rrn gene in E. coli EXCEPT 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.
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'-O
b. pyrimidine; +1; closed; 5'-O
c. purine; +2; closed; 3'-O
d. purine; −1; open; 5'-O
e. purine; +1; open; 3'-O
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
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
One of the termination mechanisms in bacteria utilizes the ____ factor that is an ATP-dependent helicase.
a. α (alpha)
b. β (beta)
c. γ (gamma)
d. ε (delta)
e. ρ (rho)
Characteristics of rho (ρ) 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.
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.
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
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
Expression of genes independently of regulation is termed:
a. negative regulation.
b. constitutive expression.
c. transcription expression.
d. repressible regulation.
e. autoregulation.
All are lac repressor 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.
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.
Which of the following is not a component of the araBAD operon?
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
When the cellular level of tryptophan decreases in 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.
Transcription in eukaryotic cells which is resistant to α-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.
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.
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.
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.
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
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.
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.
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.
The eukaryotic transcription factor that exhibits a sequence specificity for the TATA box is:
d. RNA polymerase II.
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.
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.
The recurring structural feature in DNA-binding proteins is the presence of ____ segments that fit into the ____ grove of B-DNA.
a. α-helix; major
b. β-sheet; major
c. β-turn; minor
d. β-barrel; minor
e. all are true
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.
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
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.
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.
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.
The initial event in the conversion of an hnRNA to the mature RNA which leaves the nucleus is:
a. formation of ribonucleoprotein particles (RNPs).
b. capping the 5'-end of the transcript with a guanylyl group by guanylyl transferase.
c. addition of a poly(A) tail to the 3'-end of the transcript by poly(A) polymerase.
d. splicing together of the exons.
e. transesterification reactions in lariat formation.
Which of the following is required for RNA splicing to occur?
a. a free 5´ hydroxyl created by hydrolysis of the phosphate ester bond
b. a cyclic phospodiester at the 3´ end of the RNA molecule
c. a 2´ hydroxyl group
d. the enzyme splicase
e. none of the above
Spliceosomes include all of the following EXCEPT:
a. snRNPs.
b. RNA-annealing proteins.
c. ATP-dependent RNA-unwinding proteins.
d. enzymes catalyzing transesterification of phosphoesters.
e. all are components.
Which is/are true of protein isoforms?
a. they are related polypeptides
b. they have identical structure and function
c. they are the result of different transcripts of a single gene
d. a and c
e. a, b, and c
Which is/are true of protein isoforms?
a. they are related polypeptides
b. they have identical structure and function
c. they are the result of different transcripts of a single gene
d. a and c
e. a, b, and c
During RNA chain elongation, ____ proceeds ahead of the transcription bubble introducing _____ supercoils
a. gyrase; negative
b. gyrase; positive
c. topoisomerase; negative
d. topoisomerase; positive
e. none of the above
During RNA chain elongation, ____ follows behind the transcription bubble removing _____ supercoils
a. gyrase; negative
b. gyrase; positive
c. topoisomerase; negative
d. topoisomerase; positive
e. none of the above
During RNA chain elongation gyrase proceeds ahead of the transcription bubble in order to _____.
a. remove negative supercoils by introducing positive supercoils
b. remove positive supercoils by introducing negative supercoils
c. remove negative supercoils by creating relaxed DNA
d. remove positive supercoils by creating relaxed DNA
e. none of the above