Deck 17: Transcription, Rna Processing, and Translation

Question 1

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed its 5' cap and poly-A tail. Which of the following would you expect her to find?

A) The mRNA is quickly converted into a ribosomal subunit.
B) The cell adds a new poly-A tail to the mRNA.
C) The mRNA attaches to a ribosome and is translated, but more slowly.
D) The molecule is digested by enzymes because it is not protected at the 5' end.

Answer 1

D

Question 2

Which of the following processes is central to the initiation of transcription in bacteria?

A) binding of sigma to the promoter region
B) formation of a phosphodiester bond in the elongating RNA strand
C) binding of DNA polymerase to the promoter region
D) formation of a DNA primer

Answer 2

A

Question 3

How are RNA hairpin turns related to transcriptional termination in E. coli?

A) The turns are formed from complementary base pairing and cause separation of the RNA transcript and RNA polymerase.
B) A three-base repeat signals a stop sequence, and the RNA transcript is released.
C) Release factors bind to sites on the hairpin turn, causing release of the RNA transcript.
D) The hairpin turn prevents more nucleoside triphosphates from entering the active site of the enzymes, effectively shutting off the process of polymerization.

Answer 3

A

Question 4

Use this model of a eukaryotic transcript to answer the following question(s).
Which components of the previous molecule will also be found in mRNA in the cytosol?

A) 5' UTR I1 I2 I3 UTR 3'
B) 5' E1 E2 E3 E4 3'
C) 5' UTR E1 E2 E3 E4 UTR 3'
D) 5' I1 I2 I3 3'
E) 5' E1 I1 E2 I2 E3 I3 E4 3'

Question 5

Which molecule or reaction supplies the energy for polymerization of nucleotides in the process of transcription?

A) the interaction between RNA polymerase and the promoter
B) the phosphate bonds in the nucleotide triphosphates that serve as substrates
C) the energy released when hydrogen bonds are broken as the DNA molecule is unwound
D) ATP only

Question 6

David Pribnow studied the base sequences of promoters in bacteria and bacterial viruses. He found two conserved regions in these promoters (the −10 box and the −35 box). These two regions of the promoter ________.

A) signal the initiation site
B) bind the sigma subunit that is associated with RNA polymerase
C) attach the correct nucleotide triphosphate to the template DNA strand
D) separate the two DNA strands

Question 7

The enzyme complex associated with DNA in the associated figure is ________.

A) helicase
B) DNA polymerase
C) RNA polymerase
D) topoisomerase

Question 8

What is the function of the group of amino acids on the RNA polymerase, called the rudder?

A) It provides the energy required for formation of phosphodiester bonds in the elongating RNA molecule.
B) It helps unwind and open the DNA molecule.
C) It moves template and non-template strands of DNA through channels inside the enzyme.
D) It helps sigma bind to the RNA polymerase molecule.

Question 9

Death cap mushrooms produce a substance called alpha-amanitin. Alpha-amanitin efficiently blocks synthesis of mRNA, but not of tRNA or rRNA, in eukaryotic organisms. This is possible because alpha-amanitin efficiently interferes with ________.

A) the action of RNA polymerase I, but not RNA polymerase II or III
B) RNA polymerase III, but not RNA polymerase I and II
C) the action of RNA polymerases I and II, but not RNA polymerase III
D) the action of RNA polymerase II, but not RNA polymerase I or III

Question 10

During elongation, RNA polymerase has three prominent channels, or grooves. These channels provide sites for all of the following EXCEPT ________.

A) a site for the double-stranded DNA molecule
B) a site for the entry of ribonucleoside triphosphates
C) a site for the exit of the diphosphates removed from the nucleotide triphosphates
D) a site for the growing RNA strand

Question 11

Which of the following mutations is most likely to cause a phenotypic change?

A) a duplication of all or most introns
B) a large inversion whose ends are each in the same region between genes
C) a nucleotide substitution in an exon coding for a transmembrane domain
D) a single nucleotide deletion in an exon coding for an active site
E) a frameshift mutation one codon away from the 3' end of the nontemplate strand

Question 12

Put the following events of bacterial transcription in chronological order.
1) Sigma binds to the promoter region.
2) The double helix of DNA is unwound, breaking hydrogen bonds between complementary strands.
3) Sigma binds to RNA polymerase.
4) Sigma is released.
5) Transcription begins.

A) 2, 3, 4, 5, 1
B) 2, 3, 1, 4, 5
C) 3, 1, 2, 5, 4
D) 3, 2, 1, 4, 5

Question 13

Eukaryotes have three nuclear RNA polymerases. The primary function of RNA polymerase II is transcription of ________.

A) only rRNA-coding genes
B) only tRNA-coding genes
C) both rRNA- and tRNA-coding genes
D) protein-coding genes

Question 14

You want to engineer a eukaryotic gene into a bacterial colony and have it expressed. What must be included in addition to the coding exons of the gene?

A) the introns
B) eukaryotic polymerases
C) a bacterial promoter sequence
D) eukaryotic ribosomal subunits
E) eukaryotic tRNAs

Question 15

What is responsible for termination of transcription in eukaryotic protein-coding genes?

A) a polyadenylation, or poly(A), signal
B) a termination loop composed of guanine
C) a sigma factor
D) a portion of the polymerase holoenzyme
E) three nonsense mutations in sequence

Question 16

Which one of the following statements about RNA processing is TRUE?

A) Exons are cut out before mRNA leaves the nucleus.
B) Ribozymes may function in RNA splicing.
C) RNA splicing can be catalyzed by tRNA.
D) A primary transcript is often much shorter than the final RNA molecule that leaves the nucleus.

Question 17

In E. coli, if RNA polymerase is missing ________, then transcription initiation would not occur at the appropriate initiation sites.

A) amino acids
B) mRNA
C) sigma
D) the core enzyme

Question 18

In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein?

A) RNA polymerase I
B) RNA polymerase II
C) RNA polymerase III
D) RNA polymerase IV
E) primase

Question 19

A ribozyme is ________.

A) a catalyst that uses RNA as a substrate
B) an RNA with catalytic activity
C) an enzyme that catalyzes the association between the large and small ribosomal subunits
D) an enzyme that synthesizes RNA as part of the transcription process
E) an enzyme that synthesizes RNA primers during DNA replication

Question 20

In eukaryotic cells, transcription cannot begin until ________.

A) the two DNA strands have completely separated and exposed the promoter
B) several transcription factors have bound to the promoter
C) the 5' caps are removed from the mRNA
D) the DNA introns are removed from the template
E) DNA nucleases have isolated the transcription unit

Question 21

Some viruses can be crystallized and their structures analyzed. One such virus is yellow mottle virus, which infects beans. This virus has a single-stranded RNA genome containing about 6300 nucleotides. Its capsid is 25-30 nm in diameter and contains 180 identical capsomeres. If the yellow mottle virus begins its infection of a cell by using its genome as mRNA, which of the following would you expect to be able to measure?

A) replication rate
B) transcription rate
C) translation rate
D) accumulation of new ribosomes
E) formation of new transcription factors

Question 22

Which of the following occurs in prokaryotes but not in eukaryotes?

A) post-transcriptional splicing
B) concurrent transcription and translation
C) translation in the absence of a ribosome
D) gene regulation

Question 23

An experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' bases AC. Which of the following hypotheses describes the most likely result?

A) tRNA will not form a cloverleaf.
B) The amino acid methionine will not become covalently bound.
C) The anticodon will not bind with the mRNA codon.
D) The aminoacyl-tRNA synthetase will not be formed.

Question 24

A mutant bacterial cell has a defective aminoacyl-tRNA synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. The consequence of this for the cell will be that ________.

A) none of the proteins in the cell will contain phenylalanine
B) proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU
C) the cell will compensate for the defect by attaching phenylalanine to tRNAs with lysine-specifying anticodons
D) the ribosome will skip a codon every time a UUU is encountered

Question 25

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the ________.

A) binding of ribosomes to mRNA
B) shape of the A and P sites of ribosomes
C) binding of the anticodon to a small subunit of the ribosome
D) attachment of amino acids to rRNAs
E) binding of the anticodon to the codon and the attachment of amino acids to tRNAs

Question 26

As scientists were unraveling the mysteries associated with transcription and translation in eukaryotes, they discovered there was not a one-to-one correspondence between the nucleotide sequence of a gene and the base sequence of the mRNA it codes for. They proposed the genes-in-pieces hypothesis. How can the genes-in-pieces hypothesis be explained?

A) Introns are noncoding segments of DNA that are present in the initial transcript, but are removed by splicing.
B) Introns are noncoding segments of DNA that are not read or transcribed by RNA polymerase II.
C) Exons are noncoding segments of DNA that are not read or transcribed by RNA polymerase II.
D) Exons are noncoding segments of DNA that are present in the initial transcript but are removed by splicing.

Question 27

Which of the following statements is TRUE about protein synthesis in prokaryotes?

A) Extensive RNA processing is required before prokaryotic transcripts can be translated.
B) Translation can begin while transcription is still in progress.
C) Prokaryotic cells have complicated mechanisms for targeting proteins to the appropriate cellular organelles.
D) Translation requires antibiotic activity.
E) Unlike eukaryotes, prokaryotes require no initiation or elongation factors.

Question 28

There are 61 codons that each specify the addition of a specific amino acid, and 3 stop codons for which there is no corresponding amino acid. However, there are only about 40 tRNA molecules, representing 40 anticodons. How is that possible?

A) Only about 40 of the recognized 61 codons are present in mRNA.
B) An anticodon forms hydrogen bonds with the codon; it must match the first two bases of the codon but is less specific with respect to the third base.
C) There are tRNAs that can bind one of two related amino acids.
D) Only 20 of the codons are active-one for each amino acid.

Question 29

In comparing DNA replication with RNA transcription in the same eukaryotic cell, only DNA replication ________.

A) uses RNA polymerase
B) makes a new molecule from its 5' end to its 3' end
C) occurs in the nucleus of the cell
D) incorporates the entire template molecule in the product

Question 30

Refer to the figure associated with this question. The mRNA is smaller than the length of the DNA that codes for it because ________.

A) the regulatory regions (exons) of the gene are not transcribed
B) post-transcriptional modification removes the introns
C) post-transcriptional modification removes the exons
D) bases are added to the tail of the primary transcript

Question 31

There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that ________.

A) some tRNAs have anticodons that recognize 4 or more different codons
B) the rules for base pairing between the third base of a codon and tRNA are flexible
C) many codons are never used, so the tRNAs that recognize them are dispensable
D) the DNA codes for all 61 tRNAs, but some are then destroyed
E) competitive exclusion forces some tRNAs to be destroyed by nucleases

Question 32

A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is ________.

A) TTT
B) UUA
C) UUU
D) AAA

Question 33

What molecules in the spliceosome catalyze the intron removal reactions?

A) RNA polymerases
B) ribozymes
C) tRNA
D) introns

Question 34

Codons are three-base sequences that specify the addition of a single amino acid. How do eukaryotic codons and prokaryotic codons compare?

A) Prokaryotic codons usually contain different bases than those of eukaryotes.
B) Prokaryotic codons usually specify different amino acids than those of eukaryotes.
C) The translation of codons is mediated by tRNAs in eukaryotes, but translation requires no intermediate molecules such as tRNAs in prokaryotes.
D) Codons are a nearly universal language among all organisms.

Question 35

If the sequence in the coding strand of DNA for a particular amino acid is 5'AGT3', then the anticodon on the corresponding tRNA would be ________.

A) 5'ACU3'
B) 5'TCA3'
C) 5'UCA3'
D) 5'AGU3'

Question 36

Ribosomes can attach to prokaryotic messenger RNA ________.

A) once post-transcriptional modification is complete
B) before transcription is complete
C) once replication is complete
D) once the primary transcript has been released from RNA polymerase

Question 37

Use this model of a eukaryotic transcript to answer the following question(s).
When the spliceosome binds to the transcript shown above, it can attach ________.

A) to the exons
B) to the 5' UTR
C) to the 3' UTR
D) at certain sites along an intron

Question 38

Suppose that an induced mutation removes most of the 5' end of the 5' UTR of an mRNA. What is most likely to happen?

A) Removal of the 5' UTR will have no effect because the exons are still maintained.
B) Removal of the 5' UTR also removes the 5' cap and the mRNA will quickly degrade.
C) The 3' UTR will duplicate and one copy will replace the 5' end.
D) The first exon will not be read because I1 will now serve as the UTR.

Question 39

What ensures that the correct amino acid is added during translation?

A) the anticodon of a properly formed aminoacyl tRNA
B) the methyl-guanosine cap of a properly modified mRNA
C) the poly-A tail of a properly modified mRNA
D) the twisting number of a properly supercoiled DNA

Question 40

There should be a strong positive correlation between the rate of protein synthesis and ________.

A) the quantity of DNA polymerase
B) the quantity of RNA polymerase
C) the size of mRNA
D) the number of ribosomes

Question 41

Use the following information to answer the question(s) below.
A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) in the ribosome already.
Which component of the complex described enters the exit tunnel in the large subunit of the ribosome?

A) tRNA with attached lysine (#1)
B) tRNA with polypeptide (#2)
C) tRNA that no longer has attached amino acid
D) newly formed polypeptide
E) initiation and elongation factors

Question 42

In the figure associated with this question, what is the function of the ACC sequence at the 3' end?

A) It attaches to an amino acid.
B) It base pairs with the codon of mRNA.
C) It stabilizes the tRNA-amino acid complex.
D) It is the active site of this ribozyme.

Question 43

How does termination of translation take place?

A) The end of the mRNA molecule is reached.
B) A stop codon is reached.
C) The 5' cap is reached.
D) The poly-A tail is reached.

Question 44

In the figure associated with this question, what is the function of the AGU on the loop of the tRNA?

A) It attaches to the amino acid.
B) It base pairs with a codon of mRNA.
C) It stabilizes the tRNA-amino acid complex.
D) It is the active site of this ribozyme.

Question 45

The tRNA shown with the previous question has its 3' end projecting beyond its 5' end. What will occur at this 3' end?

A) The codon and anticodon complement one another.
B) The amino acid binds covalently.
C) The excess nucleotides (ACCA) will be cleaved off at the ribosome.
D) The small and large subunits of the ribosome will attach to it.
E) The 5' cap of the mRNA will become covalently bound.

Question 46

Translation directly involves ________.

A) mRNA, tRNA, GTP, and DNA
B) mRNA, tRNA, ribosomes, and DNA
C) mRNA, ribosomes, GTP, and DNA
D) mRNA, tRNA, ribosomes, and GTP
E) tRNA, ribosomes, GTP, and DNA

Question 47

The ribosome-binding site of prokaryotes is also known as the ________.

A) TATA box
B) promoter
C) Shine-Dalgarno sequence
D) Pribnow box

Question 48

Translation requires ________.

A) mRNA, tRNA, DNA, and rRNA
B) mRNA, DNA, and rRNA
C) mRNA, tRNA, and rRNA
D) mRNA, tRNA, and DNA

Question 49

Put the following events of elongation in prokaryotic translation in chronological order.
1) Binding of mRNA with small ribosomal subunit
2) Recognition of initiation codon
3) Complementary base pairing between initiator codon and anticodon of initiator tRNA
4) Base pairing of the mRNA codon following the initiator codon with its complementary tRNA
5) Attachment of the large subunit

A) 1, 2, 3, 4, 5
B) 2, 1, 4, 3, 5
C) 5, 4, 3, 2, 1
D) 1, 2, 3, 5, 4

Question 50

The anticodon of a particular tRNA molecule is ________.

A) complementary to the corresponding mRNA codon
B) complementary to the corresponding triplet in rRNA
C) the part of tRNA that bonds to a specific amino acid
D) changeable, depending on the amino acid that attaches to the tRNA
E) catalytic, making the tRNA a ribozyme

Question 51

Which of the following is the first event to take place in translation in eukaryotes?

A) elongation of the polypeptide
B) base pairing of activated methionine-tRNA to AUG of the messenger RNA
C) binding of the larger ribosomal subunit to smaller ribosomal subunits
D) covalent bonding between the first two amino acids
E) the small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA

Question 52

Use the following information to answer the question(s) below.
A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) in the ribosome already.
Where does tRNA #2 move to after this bonding of lysine to the polypeptide?

A) A site
B) P site
C) E site
D) exit tunnel
E) directly to the cytosol

Question 53

Once a peptide bond has been formed between the amino acid attached to the tRNA in the P site and the amino acid associated with the tRNA in the A site, what occurs next?

A) translocation
B) reading of the next codon of mRNA
C) initiation
D) breaking the codon-anticodon hydrogen bonds holding the tRNA in the A site

Question 54

During elongation, which site in the ribosome represents the location where a codon is being read?

A) E site
B) P site
C) A site
D) the small ribosomal subunit

Question 55

The figure associated with this question represents a tRNA that recognizes and binds a particular amino acid (in this instance, phenylalanine). Which codon on the mRNA strand codes for this amino acid?

A) UGG
B) GUG
C) GUA
D) UUC
E) CAU

Question 56

Which of the following, if missing, would usually prevent translation from starting in eukaryotes?

A) exon
B) 5' cap
C) AUG codon
D) 5' cap or AUG codon
E) exon, 5' cap, or AUG codon

Question 57

What type of bonding is responsible for maintaining the shape of the tRNA molecule shown in the figure above?

A) covalent bonding between sulfur atoms
B) ionic bonding between phosphates
C) hydrogen bonding between base pairs
D) van der Waals interactions between hydrogen atoms
E) peptide bonding between amino acids

Question 58

Use the following information to answer the question below.
A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3'(mRNA). The following charged transfer RNA molecules (with their anticodons shown in the 3' to 5' direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form.

The anticodon loop of the first tRNA that will complement this mRNA is

A) 3' GGC 5'
B) 5' GGC 3'
C) 5' ACG 3'
D) 5' UGC 3'
E) 3' UGC 5'