Deck 16: Transcription, RNA Processing, and Translation

Question 1

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.

Answer 1

C

Question 2

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

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

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 elongation 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.

Answer 3

C

Question 4

A primary transcript in the nucleus of a eukaryotic cell is ________ the functional mRNA,while a primary transcript in a prokaryotic cell is ________ the functional mRNA.

A)the same size as;the same size as
B)larger than;the same size as
C)larger than;smaller than
D)the same size as;larger than

Question 5

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

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

Question 6

As scientists were unraveling the mysteries associated with transcription and translation,they discovered there was not a one-to-one correspondence between nucleotide sequence of a gene and 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)Several related genes are found in the genomes of humans and other animals.

Question 7

What molecule is responsible for the catalytic activity in the spliceosomes that are involved in removal of introns?

A)RNA polymerase
B)ribozymes
C)proteins of the spliceosome
D)autocatalysis by introns

Question 8

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 9

Figure 16.2
Refer to Figure 16.2.The mRNA is smaller than the length of the DNA that codes for it because

A)the regulatory regions (introns)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 10

Put the following events of 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 11

RNA polymerase needs a subunit to initiate transcription that is not needed for transcript elongation.What is the subunit?

A)Mg²⁺
B)rho
C)sigma
D)the holoenzyme

Question 12

α-amanitin is a toxin produced by the death cap mushroom.It blocks the synthesis of mRNA.What effect would it have on health of the organism that ate death cap mushrooms?

A)It would block DNA synthesis.
B)It would tie up Mg²⁺ and,through this action,inhibit glycolysis.
C)It would denature existing proteins.
D)It would cause death.

Question 13

The enzyme complex associated with DNA in the figure is

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

Question 14

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 15

The TATA box of the eukaryotic promoter is analogous to which structure of the prokaryotic promoter?

A)sigma
B)the -10 box
C)the -35 box
D)the site of initiation

Question 16

The segments of DNA where transcription begins have a binding site for RNA polymerase.These segments are known as

A)sigma.
B)the holoenzyme.
C)initiation factors.
D)promoters.

Question 17

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).What is the function of these two regions of the promoter?

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

Question 18

Which of the following is/are post-transcriptional modifications occurring in eukaryotic mRNAs?

A)addition of a poly (A)tail
B)addition of a methyl-guanosine cap
C)removal of introns
D)all of the above

Question 19

How are RNA hairpin turns related to termination?

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.

Question 20

Death cap mushrooms produce a substance called -amanitin.α-amanitin efficiently blocks synthesis of mRNA,but not of tRNA or rRNA in eukaryotic organisms.How is that possible?

A)α-amanitin efficiently interferes with the action of RNA polymerase I,but not RNA polymerase II or III.
B)α-amanitin efficiently interferes with RNA polymerase III,but not RNA polymerase I and II.
C)α-amanitin efficiently blocks the action of one or more basic transcription factors.
D)α-amanitin efficiently interferes with the action of RNA polymerase II,but not RNA polymerase I or III.

Question 21

What molecule/feature ensures that the correct amino acid is added with reading of a specific codon 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 22

Post-translational modifications include all of the following EXCEPT

A)removal of introns.
B)formation of hydrogen bonds among carbonyl and amino groups of the polypeptide backbone.
C)formation of covalent bonds between cysteine residues of the amino acid site chains.
D)addition of carbohydrates to form a glycoprotein.

Question 23

The ribosome-binding site of prokaryotes is also known as

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

Question 24

How does termination of translation take place?

A)The ribosome reaches the end of the mRNA molecule.
B)Stop codons with no corresponding tRNAs are read.
C)Hairpin turns of mRNA force the ribosome off the molecule.
D)Energy depletion causes termination.

Question 25

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 26

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 27

What is inosine,and what role does it play in translation?

A)Inosine is a purine base that,when in an anticodon opposite the third base of a codon,provides flexibility in base pairing.
B)Inosine is a sugar that,when metabolized near a ribosome,provides energy for the formation of peptide bonds.
C)Inosine is an enzyme that,when linked to the active site of a ribosome,catalyzes the process of translocation.
D)Inosine is a regulatory molecule that,when bound to a ribonuclease,controls the rate of degradation of mRNA.

Question 28

Figure 16.3
Refer to Figure 16.3.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 the codon of mRNA.
C)It stabilizes the tRNA-amino acid complex.
D)It is the active site of this ribozyme.

Question 29

Once a peptide 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,which process on the list occurs next?

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

Question 30

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

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

Question 31

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

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

Question 32

What is the function of the 3′ end of the tRNA?

A)It attaches to the 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 33

Which of the following does not play a role in the process of translation?

A)GTP
B)5' G-cap
C) tRNAs
D)exons
E)ATP

Question 34

The start codon is the same for prokaryotes and eukaryotes.What is the start codon?

A)an anticodon
B)a ribozyme
C)AUG
D)GGC

Question 35

There are 61 codons that each specify the addition of a specific amino acid,and three 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 36

A mutation that results in premature termination of translation

A)is a silent mutation.
B)is a nonsense mutation.
C)usually has no effect on the function of the protein.
D)is a missense mutation.

Question 37

Figure 16.4
Refer to Figure 16.4.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)small subunit

Question 38

Figure 16.5
Refer to Figure 16.5.The mutation resulting in sickle cell anemia is an example of a

A)point mutation.
B)frameshift mutation.
C)silent mutation.
D)deletion.

Question 39

Which of the following is NOT one of the steps in initiation of translation?

A)binding of the large ribosomal subunit to the small ribosomal subunit
B)binding of tRNA carrying formyl methionine to the start codon and small ribosomal subunit
C)recognition and binding of mRNA by the small ribosomal subunit
D)formation of a polypeptide bond