2335722
Descripción
Test por John Bench, actualizado hace más de 1 año
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Creado por John Bench
hace más de 9 años
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Pregunta 1
Pregunta
What would be the likely cellular effects of a large deletion in the gene encoding the polymerase responsible for adding 3′ poly(A) tails to eukaryotic mRNAs?
Respuesta
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Inactivation of the polymerase would lead to incomplete pre-mRNA processing, including 3′ end formation, splicing, editing, and transport—and would certainly be lethal.
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Activation of the polymerase would lead to incomplete pre-mRNA processing, including 3′ end formation, splicing, editing, and transport—and would certainly be lethal.
Pregunta 2
Pregunta
Compare and contrast splicing mechanisms used by spliceosomes, group I introns, and group II introns, with respect to the nucleophiles, proteins, or nucleic acids involved and how the specificity of splice sites is achieved.
Respuesta
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Group I and group II introns are generally self-splicing, with only the RNA backbone of the intron required for the reaction in vitro. The nucleophile in the first step, cleavage of the 5′ splice site, is a guanine nucleotide or nucleoside for group I introns, and the 2′-OH of an internal A residue for group II introns. The second step uses the liberated 3′-OH at the 5′ splice site as nucleophile to attack the phosphodiester bond at the 3′ splice site, joining the exons. Site specificity is aided by guide sequences that are part of the intron structures. Introns removed with spliceosomes follow a mechanism similar to group II introns, but also rely on the spliceosome ribonucleoprotein complex to catalyze their excision.
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None
Pregunta 3
Pregunta
Self-splicing introns do not require an energy source, such as ATP or GTP, to catalyze splicing. How does self-splicing proceed with a reasonable yield of products?
Respuesta
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Self-splicing catalyzes phosphodiester exchange reactions with no net loss or gain of energy. Bonds are broken and re-formed with different nucleotides, and there is no change in the number of phosphodiester bonds, just in the covalent bonding partners. Thus, there is no net change in free energy from reactants to products.
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none
Pregunta 4
Pregunta
Which of the following nuclear pre-mRNA nucleotide sequences potentially contains an intron?
Respuesta
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5'--UGACCAUGGCGCUAACACUGCCAAUUGGCCAAUACUGACCUGAUAGCAUCAGCCAA--3'
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5'--UAGUCUCAUCUGUCCAUUGACUUCGAAACUGAAUCGUAACUCCUACGUCUAUGGA--3'
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5'--UAGCUGUUUGUCAUGACUGACUGGUCACUAUCGUACUAACCUGUCAUGCAAUGUC--3'
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5'--UAGCAGUUCUGUCGCCUCGUGGUGCUGGCUGGCCCUUCGUCGCUCGGGCUUAGCUA--3'
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5'--UAGGUUCGCAUUGACGUACUUCUGAGACUACUAACUACUAACGCAUCGAGUCUCAA--3'
Pregunta 5
Pregunta
One of the five pre-mRNAs shown above is a likely candidate for splicing out an intron sequence. What mRNA nucleotide sequence would one expect to result from this splicing event?
Respuesta
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5'--UAGUCUCAA--3'; the putative intron from the 5' GU through the 3' AG has been removed.
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none
Pregunta 6
Pregunta
Eukaryotic messenger RNA and hnRNA both have ___________ at their 3'-ends.
Respuesta
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m7 G caps
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poly(A) tails
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hairpin structures
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covalently bound proteins
Pregunta 7
Pregunta
Eukaryotic messenger RNA molecules have _______________ at their 5' ends.
Respuesta
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m7 G caps
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poly(A) tails
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hairpin structures
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covalently bound proteins
Pregunta 8
Pregunta
Eukaryotes use a variety of pathways to form 5'-m7 G caps.
Respuesta
- True
- False
Pregunta 9
Pregunta
The carboxy terminal domain of the largest subunit of RNA polymerase II must be _______________ on Ser-5 to target a transcript for capping.
Respuesta
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methylated
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phosphorylated
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glycosylated
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dephosphorylated
Pregunta 10
Pregunta
Amino acid-coding regions within eukaryotic genes may be interrupted by ___________ regions.
Respuesta
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noncoding
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long terminal repeat
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split gene
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enhancer
Pregunta 11
Pregunta
Exons tend to be conserved during evolution, whereas introns usually are not as tightly conserved.
Respuesta
- True
- False
Pregunta 12
Pregunta
Two splicing intermediates resemble ______________.
Respuesta
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hairpins
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projections
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lariats
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helices
Pregunta 13
Pregunta
_______________ permits a cell to recode genetic information in a systematic and regulated fashion.
Respuesta
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Replication
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Transcription
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RNA editing
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DNA repair
Pregunta 14
Pregunta
Pre-mRNA requires specific sequences for precise __________ to occur.
Respuesta
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skipping
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splicing
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tagging
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replication
Pregunta 15
Pregunta
A single _____________ can be processed to produce two or more different mRNA molecules.
Respuesta
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tRNA
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pre-mRNA
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snRNP
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ribosome
Pregunta 16
Pregunta
_________________ assemble to form a spliceosome, the splicing machine that excises introns.
Respuesta
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rRNAs
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snRNPs
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tRNAs
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Micro RNAs
Pregunta 17
Pregunta
What is the key component of the catalytic site of the spliceosome?
Respuesta
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DNA
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protein
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ribisomes
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RNA
Pregunta 18
Pregunta
Transcription termination takes place downstream from the _______________
Respuesta
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5'-m7 G caps
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poly(A) site
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promoter region
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enhancer sequences
Pregunta 19
Pregunta
_________________ molecules can silence gene expression.
Respuesta
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Knockout
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Short RNA
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Spliceosome
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Protease
Pregunta 20
Pregunta
The ______________ pathway blocks mRNA translation or causes mRNA degradation.
Respuesta
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spliceosome
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miRNA
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ribozyme
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snRNP
Pregunta 21
Pregunta
Splicing begins as a cotranscriptional process and continues as a posttranscriptional process.
Respuesta
- True
- False
Pregunta 22
Pregunta
One form of severe thalassemia is known to be the result of a mutation that causes abnormal RNA splicing because of a five nucleotide deletion that disrupts the first splice donor signal of the beta globin pre-mRNA. All thalassemias result in a reduced rate of synthesis of one of the globin chains (either alpha or beta globin) that make up hemoglobin. Which of the following techniques would best show the presence of the abnormal splicing in a suspected carrier of the disease?
Respuesta
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Analysis to detect altered mobility of beta globin protein by electrophoresis
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Analysis to detect decreased oxygen binding by red blood cells
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Analysis to detect altered size of beta globin protein
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Analysis to detect altered DNA sequence of promoter regions
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Analysis to detect altered size of beta globin mRNA
Pregunta 23
Pregunta
Figure 1 represents regions around a gene encoding a mRNA. Exon I of the mRNA contains the translation initiation AUG codon. Exon IV contains the UGA termination codon. The letters A through E above the diagram refer to areas of the gene and its transcript located directly below them.
Which of the lettered regions of the primary transcript is removed by a spliceosome?
Respuesta
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A
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B
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C
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D
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E
Pregunta 24
Pregunta
Figure 1 represents regions around a gene encoding a mRNA. Exon I of the mRNA contains the translation initiation AUG codon. Exon IV contains the UGA termination codon. The letters A through E above the diagram refer to areas of the gene and its transcript located directly below them.
What region of the DNA contains the TATA box?
Respuesta
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A
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B
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C
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D
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E
Pregunta 25
Pregunta
Figure 1 represents regions around a gene encoding a mRNA. Exon I of the mRNA contains the translation initiation AUG codon. Exon IV contains the UGA termination codon. The letters A through E above the diagram refer to areas of the gene and its transcript located directly below them.
Where is the poly (A) tail added to the transcript?
Respuesta
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A
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B
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C
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D
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E
Pregunta 26
Pregunta
Figure 1 represents regions around a gene encoding a mRNA. Exon I of the mRNA contains the translation initiation AUG codon. Exon IV contains the UGA termination codon. The letters A through E above the diagram refer to areas of the gene and its transcript located directly below them.
Where is the 5' cap added to the transcript?
Respuesta
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A
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B
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C
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D
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E
Pregunta 27
Pregunta
If you used radioactively labeled mRNA produced from the galactose operon (encodes for the galE, galT, and galK genes) as a probe in a southern blot experiment, the mRNA probe would NOT hybridize to which one of following DNA sequences?
Respuesta
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The galE gene
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The galT gene
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The galK gene
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The galactose operon P1 or P2 promoters
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A bogus question. The mRNA probe would bind to each of the DNA sequences listed above
Pregunta 28
Pregunta
RNA interference (RNAi) is regulatory mechanism at the
Respuesta
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transcriptional level.
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post-transcriptional level.
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translational level.
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post-translational level.
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genomic organization level.
Pregunta 29
Pregunta
The trigger for RNA interference (RNAi) is
Respuesta
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double stranded DNA
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single stranded RNA
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double stranded RNA
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double stranded RNA to which a single strand RNA is base paired
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single stranded RNA with a nick
Pregunta 30
Pregunta
You want to clone an insert containing a gene-of-interest into a plasmid vector. Which of the following is TRUE?
Respuesta
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Both the insert and plasmid must be cut with the same restriction enzyme
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Complementary sticky ends from different DNA molecules cannot base pair
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After ligation, the next step is transposition into a bacterial host.
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A replication origin is required in both the plasmid and the insert.
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More than one of the above statements (A-D) is true
Pregunta 31
Pregunta
For the experiment below, cDNA from kidney was labeled green, and cDNA from lung was labeled red. The probes from the two samples were mixed together and hybridized to a microarray, giving the results below. The numbers represent fluorescent intensity for genes AF. Assume that the red and green fluorescent labels give equivalent signal.
kidney lung
green red
gene A 2,000 1,900
gene B 3,000 1,000
gene C 2,000 5,000
gene D 1,500 5,000
gene E 800 1,000
gene F 9,000 10,000
Which gene(s) would you select for study if you were interested in genes required specifically for kidney function?
Respuesta
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Genes F and C
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Genes F, A, and E
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Gene D
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Gene C
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Gene B
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