Deck 27: Translation

Question 1

Codons that do not specify amino acids but signal the ribosome to terminate polypeptide chain elongation are termed

A)frameshifts.
B)anticodon.
C)Stop codons.
D)suppressors.
E)terminators.

Answer 1

Stop codons.

Question 2

Matching
Choose the correct answer from the list. Not all the answers will be used.
The start codon is usually ______.

A)AUG
B)sense
C)release factors
D)noninitiator
E)hairpin
F)preproteins
G)genetic code
H)penicillin
I)proproteins
J)proofreading
K)UUA
L)synonyms
M)nucleotide cypher
N)streptomycin
O)nonsense
P)revising
Q)cloverleaf

Answer 2

AUG

Question 3

Matching
Choose the correct answer from the list. Not all the answers will be used.
At low concentrations the antibiotic ______ causes misreading of the mRNA.

A)AUG
B)sense
C)release factors
D)noninitiator
E)hairpin
F)preproteins
G)genetic code
H)penicillin
I)proproteins
J)proofreading
K)UUA
L)synonyms
M)nucleotide cypher
N)streptomycin
O)nonsense
P)revising
Q)cloverleaf

Answer 3

streptomycin

Question 4

Which of the following is a ribonucleoprotein required for the delivery of membrane and secretory proteins to the endoplasmic reticulum?

A)protein-conducting channel (PCC)
B)small ubiquitin-related modifier (SUMO)
C)trigger factor
D)calnexin
E)signal recognition particles (SRP)

Question 5

Matching
Choose the correct answer from the list. Not all the answers will be used.
The fidelity of amino acid attachment to a tRNA is enhanced by the ______ ability of the corresponding aaRS.

A)AUG
B)sense
C)release factors
D)noninitiator
E)hairpin
F)preproteins
G)genetic code
H)penicillin
I)proproteins
J)proofreading
K)UUA
L)synonyms
M)nucleotide cypher
N)streptomycin
O)nonsense
P)revising
Q)cloverleaf

Question 6

Matching
Choose the correct answer from the list. Not all the answers will be used.
A mutation that converts an aminoacyl-coding codon to a Stop codon is known as a ______ mutation.

A)AUG
B)sense
C)release factors
D)noninitiator
E)hairpin
F)preproteins
G)genetic code
H)penicillin
I)proproteins
J)proofreading
K)UUA
L)synonyms
M)nucleotide cypher
N)streptomycin
O)nonsense
P)revising
Q)cloverleaf

Question 7

In E.coli, base-pairing between an mRNA's ______ and the 3 end of the 16S rRNA permits the ribosome to select the proper initiation codon, thus minimizing ______.

A)start codon; abortive initiation
B)Shine-Dalgarno sequence; abortive initiation
C)start codon; frameshift mutations
D)Shine-Dalgarno sequence; frameshift mutations
E)none of the above

Question 8

In E.coli, which of the following factors function to ensure the proper binding of tRNA_f^Met during mRNA binding and ribosomal subunit assembly?
I.IF-1
II.IF-2
III.IF-3
IV.EF-Ts

A)I only
B)I, II
C)I, III
D)II, IV
E)I, II, III

Question 9

Insertions or deletions of one or two nucleotides can cause

A)frameshift mutations.
B)degenerate mutations.
C)synonymous mutations.
D)wobble codons.
E)transpeptidation.

Question 10

Matching
Choose the correct answer from the list. Not all the answers will be used.
EF-Tu binds all ______ aminoacyl tRNAs but that of tRNA^sec.

A)AUG
B)sense
C)release factors
D)noninitiator
E)hairpin
F)preproteins
G)genetic code
H)penicillin
I)proproteins
J)proofreading
K)UUA
L)synonyms
M)nucleotide cypher
N)streptomycin
O)nonsense
P)revising
Q)cloverleaf

Question 11

Proteins are properly folded with the assistance of

A)protein-conducting channels (PCCs).
B)small ubiquitin-related modifiers (SUMOs).
C)trigger factors.
D)chaperones.
E)signal recognition particles (SRPs).

Question 12

Matching
Choose the correct answer from the list. Not all the answers will be used.
Some proteins are synthesized as inactive precursors called ______.

A)AUG
B)sense
C)release factors
D)noninitiator
E)hairpin
F)preproteins
G)genetic code
H)penicillin
I)proproteins
J)proofreading
K)UUA
L)synonyms
M)nucleotide cypher
N)streptomycin
O)nonsense
P)revising
Q)cloverleaf

Question 13

The thermodynamic requirement for proofreading is met by

A)aminoacyl-tRNA binding to the ribosomal A site.
B)hydrolysis of GTP by EF-Tu
C)transpeptidation mediated by IF-2.
D)transpeptidation mediated by RF-3
E)none of the above.

Question 14

Matching
Choose the correct answer from the list. Not all the answers will be used.
Almost all known tRNAs can be arranged in the so-called ______ secondary structure.

A)AUG
B)sense
C)release factors
D)noninitiator
E)hairpin
F)preproteins
G)genetic code
H)penicillin
I)proproteins
J)proofreading
K)UUA
L)synonyms
M)nucleotide cypher
N)streptomycin
O)nonsense
P)revising
Q)cloverleaf

Question 15

Inhibitors of translation may be effective as

A)antibiotics.
B)anticancer agents.
C)research on translation.
D)all of the above
E)none of the above

Question 16

Matching
Choose the correct answer from the list. Not all the answers will be used.
Translation termination requires ______ that recognize Stop codons.

A)AUG
B)sense
C)release factors
D)noninitiator
E)hairpin
F)preproteins
G)genetic code
H)penicillin
I)proproteins
J)proofreading
K)UUA
L)synonyms
M)nucleotide cypher
N)streptomycin
O)nonsense
P)revising
Q)cloverleaf

Question 17

The correct amino acid is covalently attached to a tRNA by the corresponding ______ which is specific for each ______.

A)aminoacyl-tRNA synthetase (aaRS); amino acid
B)aminoacyl-tRNA synthetase (aaRS); species
C)elongation factor; amino acid
D)elongation factor; species
E)none of the above

Question 18

Matching
Choose the correct answer from the list. Not all the answers will be used.
Codons that specify the same amino acid are called ______.

A)AUG
B)sense
C)release factors
D)noninitiator
E)hairpin
F)preproteins
G)genetic code
H)penicillin
I)proproteins
J)proofreading
K)UUA
L)synonyms
M)nucleotide cypher
N)streptomycin
O)nonsense
P)revising
Q)cloverleaf

Question 19

Matching
Choose the correct answer from the list. Not all the answers will be used.
The ______ is composed of three-nucleotide codons that do not overlap and are read sequentially by the protein-synthesizing machinery.

A)AUG
B)sense
C)release factors
D)noninitiator
E)hairpin
F)preproteins
G)genetic code
H)penicillin
I)proproteins
J)proofreading
K)UUA
L)synonyms
M)nucleotide cypher
N)streptomycin
O)nonsense
P)revising
Q)cloverleaf

Question 20

The structural similarities of EF-G and the EF-Tu·tRNA complex indicate

A)EF-G may be used as a substitute for EF-Tu.
B)EF-G may play a role in displacing the tRNA growing peptide.
C)EF-G may mediate a change in conformation that facilitates EF-Tu binding.
D)EF-G may be involved in facilitating binding of initiation factors.
E)EF-G and EF-Tu are both required for proper initiation.

Question 21

Which of the following is TRUE regarding the Shine-Dalgarno sequence?

A)It functions as a promoter sequence which recognizes and bonds the sigma factor.
B)It is part of the operator sequence used to control translation.
C)It is a nucleotide sequence involved in initiation of translation.
D)It is a nucleotide sequence involved in termination of translation.
E)none of the above

Question 22

Which of following describes proofreading for the addition of amino acids (AAs)to the growing peptide?

A)An RNA component of the ribosome ensures that the correct AA is associated with the A site before addition occurs.
B)An RNA component of the ribosome ensures that the correct AA has been added, but before the peptidyl-tRNA is shifted to the P site.
C)The EF-Tu • GTP complex ensures that the correct AA is associated with the A site before addition occurs.
D)EF-G ensures that the correct AA has been added, but before the peptidyl-tRNA is shifted to the P -site.
E)No proofreading of this process occurs.

Question 23

Which of the following is NOT a feature of tRNA structure?

A)acceptor or amino acid stem
B)D arm
C)anticodon loop
D)3 terminal phosphate arm
E)variable arm

Question 24

Class I and Class II aminoacyl-tRNA synthetases differ in their
I.structural motifs.
II.anticodon recognition.
III.site of aminoacylation.
IV.amino acid specificity.

A)I only
B)II, III
C)II, IV
D)II only
E)I, II, III, IV

Question 25

Which linkage best describes the covalent bond between an amino acid (AA)and its cognate tRNA?

A)amino group of AA linked to 5' -OH of tRNA
B)amino group of AA linked to 5' phosphate of tRNA
C)carboxyl group of AA linked to 3' -OH of tRNA
D)carboxyl group of AA linked to 3' phosphate of tRNA
E)none of the above

Question 26

During translation, translocation of the ribosome is driven by which of the following?

A)ATP → ADP + P_i
B)ATP → AMP + PP_i
C)GTP → GDP + P_i
D)GTP → GMP + PP_i
E)Release of the tRNA in the P site

Question 27

Polypeptide synthesis

A)proceeds from the C-terminus to the N-terminus.
B)proceeds from the N-terminus to the C-terminus.
C)proceeds in both directions simultaneously.
D)proceeds in either direction once initiated.
E)proceeds randomly.

Question 28

Which of the following is NOT associated with eukaryotic translation initiation?

A)Shine-Dalgarno sequence
B)a formylated Met−tRNA_f^met
C)base pairing between the mRNA and 16S rRNA
D)initiation factors IF-1, IF-2, and IF-3
E)all of the above

Question 29

The signal recognition particle (SRP)is a _____, and its function is to ______.

A)DNA:protein complex, transport proteins into the eukaryotic nucleus
B)multisubunit protein, modify proteins
C)ribosome complex, catalyze posttranslational modification
D)ribonucleoprotein, bind the N-terminal end of growing polypeptides for membrane translocation
E)none of the above

Question 30

The steps required for peptide elongation at the ribosome are, respectively,

A)initiation, elongation and termination.
B)decoding, transpeptidation, and translocation.
C)initiation, elongation, and release.
D)aa-tRNA binding, GTP-peptidation, and translocation.
E)none of the above

Question 31

Which of the following best describes the method used for error minimization or proofreading to ensure the correct charging of the tRNAs?

A)The enzymes catalyzing the addition always proofread after the first step.
B)The enzymes catalyzing the addition always proofread after the second step.
C)Some of the enzymes catalyzing the addition proofread after the first step, some after the second.
D)Ribosomes themselves proofread the linkage when the AA-tRNA reaches the A site.
E)No proofreading of this process occurs.

Question 32

The triplet code allows many amino acids to be specified by more than one codon.Such a code is said to be

A)replicative.
B)synonymous.
C)duplicative.
D)universal.
E)degenerate.

Question 33

Which of the following best describes the preparation of fMet-tRNA_f^met for translation in prokaryotes?

A)Met is first formylated, then added to a tRNA specific for the start codon that differs from that designed to carry Met.
B)Met is first added to a tRNA specific for the start codon that differs from that designed to carry Met, then is formylated.
C)Met is first formylated, then added to a "regular" tRNA; the fact that it has the formyl group allows use in the initiation codon.
D)Met is first added to a "regular" tRNA, then is formylated; the fact that it has the formyl group allows use in the initiation codon.
E)f-Met isn't used in prokaryotes, only in eukaryotes.

Question 34

Posttranslational modifications to proteins include all of the following, except

A)glycosylation.
B)phosphorylation.
C)amino acid derivatization.
D)peptide joining.
E)proteolysis.

Question 35

Which of following best describes the process for attachment of amino acid to the appropriate tRNAs? (Note: AA = amino acid, P_i = phosphate, PP_i = pyrophosphate)

A)AA + ATP → AA-P + ADP then AA-P + tRNA → AA-tRNA + P_i
B)AA + ATP → AA-AMP + PP_i thenAA-AMP + tRNA → AA-tRNA + AMP
C)tRNA + ATP → tRNA-P + ADP then tRNA-P + AA → AA-tRNA + P_i
D)tRNA + ATP → tRNA-AMP + PP_i then tRNA-AMP + AA → AA-tRNA + AMP
E)AA + GTP → AA-GMP + PP_i then AA-GMP + tRNA → AA-tRNA + GMP

Question 36

Based on the structure shown below, which of the following correctly represents the sequence that would be present at the "XYZ" position?

A)UGG
B)TGG
C)ACC
D)Cannot be determined from the given data.
E)None of the above is the correct sequence.

Question 37

Which of the following correctly describes the sequence of events in formation of the ribosome assembly and associated RNAs and proteins?

A)small ribosome subunit associates with large subunit; mRNA associates next; IF with bound NTP brings in first f-Met-tRNA; IF then hydrolyses bound NTP.
B)IF with bound NTP binds f-Met-tRNA; small ribosome subunit associates next; mRNA associates next; then large subunit; IF then hydrolyses bound NTP.
C)small subunit associates with mRNA; IF w/ bound NTP brings in first f-Met-tRNA; IF then hydrolyses bound NTP; large subunit associates
D)large subunit associates with mRNA; IF w/ bound NTP brings in first f-Met-tRNA; small subunit associates; IF then hydrolyses bound NTP.
E)none of the above

Question 38

The site on the ribosome complex which binds the new incoming amino acid- tRNA is called the

A)P site.
B)A site.
C)E site.
D)50 S site.
E)30 S site.

Question 39

During translation, the reaction catalyzed by peptidyl transferase is coupled to which of the following?

A)ATP → ADP + P_i
B)ATP → AMP + PP_i
C)GTP → GDP + P_i
D)GTP → GMP + PP_i
E)Release of the tRNA in the P site

Question 40

What happens when a stop codon is reached by a ribosome?

A)A termination tRNA^ter binds to the codon and is used to release the growing peptide from the P site tRNA.The ribosome then is likely to dissociate.
B)A termination tRNA^ter binds to the codon and the growing peptide is transferred to it.When the peptidyl-tRNA^ter reaches the P site, the ribosome is signaled to release the protein.The ribosome then is likely to dissociate.
C)A termination tRNA^ter binds to the codon and the growing peptide is transferred to it.When the peptidyl-tRNA^ter reaches the P site, the ribosome dissociates.A separate peptidyl transferase then releases the protein from tRNA^ter.
D)A release factor binds to the codon and is used to release the growing peptide from the P site tRNA.
E)A release factor binds to the codon and the ribosome dissociates.A separate peptidyl transferase then releases the protein from the last tRNA to which was attached.

Question 41

A mutation in the DNA sequence prior to (on the 5ꞌside of)the ATG start site will result in which of the following?
I.decreased binding efficiency of the TATA binding protein
II.decreased promoter efficiency
III.frameshift mutation

A)I
B)II
C)III
D)I, II
E)I, II, III

Question 42

Which of the following best describes the wobble hypothesis?
I.The degree of variance in base pairing is greater at the 5' end of the anticodon, thus accounting for more than one codon.
II.The degree of variance in base pairing is greater at the 3' end of the anticodon, thus accounting for more than one codon
III.Non-Watson-Crick base pairing is sometimes allowed in the last position of the anticodon-codon pairing.

A)I only
B)II only
C)I and III
D)II and III
E)III only

Question 43

Structural studies of the bacterial ribosome indicate which of the following important points regarding function?

A)The domains of the 30S subunit appear flexible during protein synthesis.
B)The large subunit of the ribosome appears to undergo domain motion during protein synthesis.
C)The small and large subunits of the ribosome appear static throughout protein synthesis.
D)all of the above
E)none of the above

Question 44

Which of the following is(are)used to assist in protein folding?
I.calnexin
II.calreticulin
III.DnaK
IV.GroEL

A)I, II
B)III, IV
C)II, IV
D)I, III
E)I, II, III, IV

Question 45

The Shine-Dalgarno sequence is

A)used to align ribosome subunits and initiation translation.
B)functions as a stop codon.
C)is used to align RNA polymerase.
D)is used during transcription termination.
E)all of the above

Question 46

A silent mutation occurs when a nucleotide mutation results in the identical amino acid in place upon completion of translation.If the original sequence is as follows, which example below represents a silent mutation?
GUACAAGCAUGAAGUUUGGUAAGCG

A)GUGCAAGCAUGAAGUUUGGUAAGCG
B)GUACAAGCAUGAAAUUUGGUAAGCG
C)GUACAAGCAUGAAGUUGGGUAAGCG
D)GUACAGGCAUGAAGUUUGGUAAGCG
E)GUACAAGCAUGAAGUUUGGUAACCG

Question 47

Considering elongation of peptides via ribosome-mediated peptide synthesis, how many ATP equivalents are required for addition of on amino acid to the growing peptide chain and translocation such that the assembly is prepared for the subsequent addition of another amino acid?

A)0
B)1
C)2
D)3
E)4

Question 48

The sequence steps involved in elongation of the newly synthesized protein are ordered as follows: (Note: AA=amino acid)

A)AA-tRNA binding, peptide bond formation, translocation, tRNA release.
B)translocation, AA-tRNA binding, tRNA release, peptide bond formation.
C)tRNA release, AA-tRNA binding, translocation, peptide bond formation.
D)translocation, peptide bond formation, AA-tRNA binding, tRNA release.
E)peptide bond formation, tRNA release, AA-tRNA binding, translocation.

Question 49

Which of the following is a function of the ribosome?
I.bind mRNA and allow codon recognition
II.mediate the binding of proteins necessary for initiation, elongation, and termination
III.catalyze synthesis of peptide bonds
IV.translocates such that multiple codons can be read

A)I only
B)I, II
C)I, IV
D)II only
E)I, II, III, IV