Deck 31: Post-Transcriptional Regulation of Gene Expression

Question 1

Synthesized mRNAs containing mutations could potentially lead to the synthesis of toxic proteins.Which of the following mechanisms eliminates these mRNAs?

A)by nonsense-mediated decay (NMD)
B)by stabilizing RNA-binding proteins (RBPs)
C)by AU-rich elements
D)by premature termination codons (PTCs)

Answer 1

A

Question 2

Which of the following AUBPs is known to function by out-competing other AUBPs for binding to AREs?

A)TTP
B)AUF-1
C)KSRP
D)HuR

Answer 2

D

Question 3

Which of the following is a part of the eukaryotic deadenylation process?

A)adenylation of circularized mRNA
B)an increase in binding sites for PABP
C)mRNA linearization once the poly(A)tail is down to approximately 80 nucleotides
D)decreased interaction between PABP and eIF4G

Answer 3

D

Question 4

Which of the following is an example of a Class II ARE-containing mRNA?

A)c-myc
B)TNFa
C)GLUT1
D)c-fos

Question 5

Which of the following is a characteristic of ARE-containing mRNAs?

A)Class II AREs consist of at least 2 overlapping copies of UUAUUUA(U/A)(U/A).
B)Class I AREs contain 1-3 copies of the pentanucleotide AUUUA with only A-rich regions.
C)Class III AREs contain a U-rich sequence with the typical AUUUA element.
D)Approximately 18% of analyzed human mRNA sequences belong to the ARE-containing family.

Question 6

Which of the following amino acid residues determine the binding specificity of AUBPs to RNP motif-1 (RNP1)and RNP motif-2 (RNP2)?

A)3 His/3 Lys
B)3 Lys/3 Cys
C)3 Arg/3 Lys
D)3 Cys/3 Arg

Question 7

Which of the following best defines miRNAs?

A)non-coding RNAs that modulate the transcription of mRNA
B)non-coding RNAs that modulate the translation of mRNA
C)coding RNAs that modulate the transcription of mRNA
D)coding RNAs that modulate the translation of mRNA

Question 8

Shortening of the poly(A)tail is mediated by enzyme complexes known as deadenylases.Which of the following is NOT a eukaryotic deadenylase?

A)UTR
B)PAN₂-PAN3
C)CCR4-NOT
D)PARN

Question 9

Which of the following repeating nucleotide motifs are contained in AREs?

A)UAAAU
B)AUAUA
C)UAUAU
D)AUUUA

Question 10

Which of the following is NOT used to measure the decay of an mRNA transcript?

A)actinomycin D
B)a-amanitin
C)5,6-dichloro-1-b-D-ribobenzimidazole (DRB)
D)puromycin

Question 11

Which of the following is a feature of oncoprotein mRNA?

A)The AMD extends the mRNA lifetime of the proto-oncogene.
B)It contains a 3' translated region (3'UTR)rich in A and U elements.
C)It is highly stable.
D)Its decay pathway is through AU-rich mediated decay (AMD).

Question 12

Which of the following is NOT a protein component of P-bodies?

A)Edc3p: decapping activator
B)Argonautes: miRNA silencing
C)CPEB: cytoplasmic polyadenylation element-binding protein
D)eIF2: eukaryotic initiation factor

Question 13

Which of the following describes the physiological significance of AMD?

A)AMD can serve as a regulator of gene expression during a drop in blood pH.
B)Removal of the ARE located in the 3'UTR of c-fos mRNA leads to increased oncogenicity of c-Fos.
C)Neuroblastoma has been linked to a significant decrease in c-myc and c-fos mRNA half-lives.
D)Blocking the access of AMD machinery to AREs inversely correlates with life-threatening diseases.

Question 14

Which of the following components protects mRNAs from cellular nucleases?

A)5'-GTP cap
B)introns
C)phosphorylation
D)TATA box

Question 15

Which of the following is a characteristic of the exosome?

A)It is a dimer-enzyme complex.
B)It avoids indiscriminate degradation of cellular RNAs.
C)It harbours 5'→3' exoribonuclease activity.
D)It has a fundamental structural pattern consisting of 6 domains arranged in a ring with a central cavity.

Question 16

Which of the following describes the RNA recognition motif (RRM)?

A)4 antiparallel b-sheets and 2 a helices
B)2 antiparallel b-sheets and 4 a helices
C)2 antiparallel b-sheets and 2 a helices
D)4 antiparallel b-sheets and 4 a helices

Question 17

Which of the following best describes the term mRNA half-life?

A)the length of time an mRNA molecule takes to degrade
B)the length of time an mRNA molecule takes to be modified
C)the length of time an mRNA molecule is stable inside the cell
D)the length of time an mRNA molecule takes to be synthesized

Question 18

Which of the following is a characteristic of P-bodies?

A)They are mitochondrial foci consisting of RNA-protein complexes.
B)Under stress conditions they typically reduce their sizes.
C)They are aggregates of messenger ribonucleoproteins (mRNPs)and P-body components.
D)They are aggregates of messenger ribonucleoproteins (mRNPs)and P-body components.

Question 19

Which of the following ARE-binding proteins (AUBPs)stabilizes ARE-mRNA?

A)KSRP
B)TTP
C)HuR
D)BRF1

Question 20

Which of the following techniques is used to determine the steady-state level of a particular mRNA at any given time?

A)Southern blot analysis
B)Northern blot analysis
C)SDS-PAGE
D)column chromatography

Question 21

Which of the following techniques can be used to identify RBP-mRNA interactions?

A)SDS-PAGE
B)Southern blot analysis
C)RNA-EMSA
D)RT-PCR

Question 22

Which of the following do miRNAs binds?

A)GREs
B)seed elements
C)AREs
D)core promoters

Question 23

Which of the following is a characteristic of siRNA?

A)introduced into tissue culture cells by transfection
B)chemically synthesized 10 nt dsRNA molecule
C)exhibits maximal RNAi activity approximately 7 days after transfection
D)enters the miRNA processing pathway at the level of the gene

Question 24

Which of the following is GRE-mediated mRNA decay (GMD)dependent upon?

A)RNP1
B)ARE
C)AUBP
D)CUGBP1

Question 25

What does the -55 boundary rule signify with respect to NMD?

A)Only stop codons at least 55 nt downstream of the final intron trigger NMD.
B)Only stop codons at least 55 nt upstream of the final intron trigger NMD.
C)Only stop codons at least 55 nt downstream of the first intron trigger NMD.
D)Only stop codons at least 55 nt upstream of the first intron trigger NMD.

Question 26

Which of the following is a characteristic of non-stop decay (NSD)?

A)It is used to accumulate mRNAs devoid of a stop codon.
B)Stalling of the ribosome at the 5'-end of the transcript recruits the cytoplasmic exosome.
C)The exosome has a number of 5'→3' exonucleases
D)Decay proceeds without the need for deadenylation and decapping.

Question 27

How do mammalian cells distinguish between PTCs and proper stop codons?

A)using AREs
B)using RNP1 and RNP2
C)using the EJC
D)using GMD

Question 28

Which of the following is NOT a part of the "unified theory of gene expression"?

A)Eukaryotic gene expression is a discontinuous process consisting of multiple steps.
B)It includes transcription,processing,and protein synthesis.
C)It depends on an interacting network of protein machines.
D)Proteins involved in mRNA export to the cytoplasm for translation are part of the theory.

Question 29

Which of the following levels of translation is NOT repressed by miRNAs?

A)ribosomal assembly
B)elongation
C)termination
D)initiation

Question 30

Which of the following is a characteristic of the AGO family?

A)They dissociate from the RISC to cleave the miRNA duplex.
B)AGO₂ participates indirectly in miRNA-mediated mRNA silencing in mammalian cells.
C)The core components are exonucleases.
D)They are composed of 3 well-conserved domains (MID,PIW1,PA2).

Question 31

Which of the following specifies the order of assembly for some of the EJC proteins with target mRNAs?

A)UPF3;REF;UPF1;UPF2
B)UPF2;UPF1;REF;UPF3
C)REF;UPF3;UPF2;UPF1
D)UPF1;REF;UPF3;UPF2

Question 32

Which of the following is NOT stored in P-bodies?

A)CCR4-NOT
B)DCP1/DCP2
C)repressed mRNAs
D)AREs

Question 33

Which of the following techniques makes use of photoactivatable ribonucleosides?

A)PAR-CLIP
B)RIP-Chip
C)RNA-EMSA
D)RBP-mRNA-PCR

Question 34

Which of the following carriers of siRNA is NOT correctly paired with its mechanism of delivery?

A)chemically synthesized siRNA: transfection protocol
B)lentivirus: transfection only into dividing cells
C)adenovirus: transient expression with DNA integration
D)retrovirus: high transfection efficiency

Question 35

Which of the following are higher-order RNA regulons?

A)3'UTR regions containing AU rich elements grouped by specific interaction with 1 or more RBPs
B)mRNAs encoding functionally related proteins grouped by specific interaction with 1 or more RBPs
C)3'UTR regions containing GU-rich elements grouped by specific interaction with 1 or more RBPs
D)mRNAs encoding functionally different proteins grouped by specific interaction with 1 or more RBPs

Question 36

Which of the following is a characteristic of RNA inference (RNAi)?

A)It is conducted by non-coding RNA (miRNAs).
B)It is mediated by cis-acting,single-stranded RNA.
C)It is conserved in a few organisms.
D)It is no longer used for conducting biological research.

Question 37

Which of the following cleaves the pre-miRNA at the level of the loop,yielding a 22-nt,double-stranded RNA molecule?

A)Drosha
B)DGCR8
C)Dicer
D)RISC

Question 38

Which of the following compounds identifies the structure below?

A)4SU
B)5BrU
C)5IU
D)6SG