Bio: Chapter 17 Translation test questions

B

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 dipeptide that will form will be A) cysteine-alanine. B) proline-threonine. C) glycine-cysteine. D) alanine-alanine. E) threonine-glycine.

A

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. 70) 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'

C

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. E) either UAA or TAA, depending on first base wobble

C

A peptide has the sequence NH2-phe-pro-lys-gly-phe-pro-COOH. Which of the following sequences in the coding strand of the DNA could code for this peptide? A) 3' UUU-CCC-AAA-GGG-UUU-CCC B) 3' AUG-AAA-GGG-TTT-CCC-AAA-GGG C) 5' TTT-CCC-AAA-GGG-TTT-CCC D) 5' GGG-AAA-TTT-AAA-CCC-ACT-GGG E) 5' ACT-TAC-CAT-AAA-CAT-TAC-UGA

E

A possible sequence of nucleotides in the template strand of DNA that would code for the polypeptide sequence phe-leu-ile-val would be A) 5' TTG-CTA-CAG-TAG 3'. B) 3' AAC-GAC-GUC-AUA 5'. C) 5' AUG-CTG-CAG-TAT 3'. D) 3' AAA-AAT-ATA-ACA 5'. E) 3' AAA-GAA-TAA-CAA 5'.

E

A frameshift mutation could result from A) a base insertion only. B) a base deletion only. C) a base substitution only. D) deletion of three consecutive bases. E) either an insertion or a deletion of a base.

B

A mutant bacterial cell has a defective aminoacyl 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. E) none of the options will occur; the cell will recognize the error and destroy the tRNA.

C

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. 76) 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

D

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. 77) Which component of the complex described enters the exit tunnel through 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

E

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) bonding of the anticodon to the codon. D) attachment of amino acids to tRNAs. E) bonding of the anticodon to the codon and the attachment of amino acids to tRNAs.

C

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' AC. Which of the following hypotheses describes the most likely result? A) tRNA will not form a cloverleaf. B) The nearby stem end will pair improperly. C) The amino acid methionine will not bind. D) The anticodon will not bind with the mRNA codon. E) The aminoacylsynthetase will not be formed.

A

DNA template strand 5' ____________________________ 3' DNA complementary strand 3' ____________________________ 5' 67) Given the locally unwound double strand above, in which direction does the RNA polymerase move? A) 3' → 5' along the template strand B) 5' → 3' along the template strand C) 3' → 5' along the complementary strand D) 5' → 3' along the complementary strand E) 5' → 3' along the double-stranded DNA

B

DNA template strand 5' ____________________________ 3' DNA complementary strand 3' ____________________________ 5' 68) In the transcription event of the previous DNA, where would the promoter be located? A) at the 3' end of the newly made RNA B) to the right of the template strand C) to the left of the template strand D) to the right of the sense strand E) to the left of the sense strand

E

In comparing DNA replication with RNA transcription in the same cell, which of the following is true only of replication? A) It uses RNA polymerase. B) It makes a new molecule from its 5' end to its 3' end. C) The process is extremely fast once it is initiated. D) The process occurs in the nucleus of a eukaryotic cell. E) The entire template molecule is represented in the product.

B

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.

C

In order for a eukaryotic gene to be engineered into a bacterial colony to be 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

C

Of the following, which is the most current description of a gene? A) a unit of heredity that causes formation of a phenotypic characteristic B) a DNA subunit that codes for a single complete protein C) a DNA sequence that is expressed to form a functional product: either RNA or polypeptide D) a DNA—RNA sequence combination that results in an enzymatic product E) a discrete unit of hereditary information that consists of a sequence of amino acids

C

Suppose that a mutation alters the formation of a tRNA such that it still attaches to the same amino acid (phe) but its anticodon loop has the sequence AAU that binds to the mRNA codon UUA (that usually specifies leucine leu). A) The modified tRNA will cause this mRNA to make only nonfunctioning product. B) The tRNA-leu will not be able to enter the site of the ribosome to bind to the UUA. C) One mutated tRNA molecule will be relatively inconsequential because it will compete with many "normal" ones. D) The tRNA will be so unstable that it will not participate in translation. E) The mutated tRNA will result in an amino acid variant in all copies of the protein.

A

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.

D

The figure represents 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) GCC E) CAU

D

The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in A) a base-pair substitution. B) a nucleotide mismatch. C) a frameshift mutation. D) a polypeptide missing an amino acid. E) a nonsense mutation.

B

The process of translation, whether in prokaryotes or eukaryotes, requires tRNAs, amino acids, ribosomal subunits, and which of the following? A) polypeptide factors plus ATP B) polypeptide factors plus GTP C) polymerases plus GTP D) SRP plus chaperones E) signal peptides plus release factor

B

The tRNA shown in the figure 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.

B

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 four 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.

A

Which of the following is not true of RNA processing? A) Exons are cut out before mRNA leaves the nucleus. B) Nucleotides may be added at both ends of the RNA. C) Ribozymes may function in RNA splicing. D) RNA splicing can be catalyzed by spliceosomes. E) A primary transcript is often much longer than the final RNA molecule that leaves the nucleus.

C

What amino acid sequence will be generated, based on the following mRNA codon sequence? 5' AUG-UCU-UCG-UUA-UCC-UUG 3' A) met-glu-arg-arg-glu-leu B) met-arg-glu-arg-glu-arg C) met-ser-ser-leu-ser-leu D) met-ser-leu-ser-leu-ser

D

What amino acid sequence will be generated, based on the following mRNA codon sequence? 5' AUG-UCU-UCG-UUA-UCC-UUG 3' A) met-arg-glu-arg-glu-arg B) met-glu-arg-arg-glu-leu C) met-ser-leu-ser-leu-ser D) met-ser-ser-leu-ser-leu E) met-leu-phe-arg-glu-glu

C

What is the effect of a nonsense mutation in a gene? A) It changes an amino acid in the encoded protein. B) It has no effect on the amino acid sequence of the encoded protein. C) It introduces a premature stop codon into the mRNA. D) It alters the reading frame of the mRNA. E) It prevents introns from being excised.

A

What is the function of GTP in translation? A) GTP energizes the formation of the initiation complex, using initiation factors. B) GTP hydrolyzes to provide phosphate groups for tRNA binding. C) GTP hydrolyzes to provide energy for making peptide bonds. D) GTP supplies phosphates and energy to make ATP from ADP. E) GTP separates the small and large subunits of the ribosome at the stop codon.

B

What is the function of the release factor (RF)? A) It separates tRNA in the A site from the growing polypeptide. B) It binds to the stop codon in the A site in place of a tRNA. C) It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond. D) It supplies a source of energy for termination of translation. E) It releases the ribosome from the ER to allow polypeptides into the cytosol.

C

What type of bonding is responsible for maintaining the shape of the tRNA molecule? 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

B

When the function of the newly made polypeptide is to be secreted from the cell where it has been made, what must occur? A) It must be translated by a ribosome that remains free of attachment to the ER. B) Its signal sequence must target it to the ER, from which it goes to the Golgi. C) It has a signal sequence that must be cleaved off before it can enter the ER. D) It has a signal sequence that targets it to the cell's plasma membrane where it causes exocytosis. E) Its signal sequence causes it to be encased in a vesicle as soon as it is translated.

A

When the ribosome reaches a stop codon on the mRNA, no corresponding tRNA enters the A site. If the translation reaction were to be experimentally stopped at this point, which of the following would you be able to isolate? A) an assembled ribosome with a polypeptide attached to the tRNA in the P site B) separated ribosomal subunits, a polypeptide, and free tRNA C) an assembled ribosome with a separated polypeptide D) separated ribosomal subunits with a polypeptide attached to the tRNA E) a cell with fewer ribosomes

B

When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by A) a specific characteristic of the ribosome itself, which distinguishes free ribosomes from bound ribosomes. B) a signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane. C) moving through a specialized channel of the nucleus. D) a chemical signal given off by the ER. E) a signal sequence of RNA that precedes the start codon of the message.

B

Which component is not directly involved in translation? A) mRNA B) DNA C) tRNA D) ribosomes E) GTP

A

Which of the following DNA mutations is the most likely to be damaging to the protein it specifies? A) a base-pair deletion B) a codon substitution C) a substitution in the last base of a codon D) a codon deletion E) a point mutation

D

Which of the following is a function of a signal peptide? A) to direct an mRNA molecule into the cisternal space of the ER B) to bind RNA polymerase to DNA and initiate transcription C) to terminate translation of the messenger RNA D) to translocate polypeptides across the ER membrane E) to signal the initiation of transcription

D

Which of the following is not true of a codon? A) It consists of three nucleotides. B) It may code for the same amino acid as another codon. C) It never codes for more than one amino acid. D) It extends from one end of a tRNA molecule. E) It is the basic unit of the genetic code.

E

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 recognizes and attaches to the 5' cap of mRNA

D

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 intergenic regions 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

E

Which of the following mutations would be most likely to have a harmful effect on an organism? A) a nucleotide-pair substitution B) a deletion of three nucleotides near the middle of a gene C) a single nucleotide deletion in the middle of an intron D) a single nucleotide deletion near the end of the coding sequence E) a single nucleotide insertion downstream of, and close to, the start of the coding sequence

B

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.

B

Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product? A) a deletion of a codon B) a deletion of two nucleotides C) a substitution of the third nucleotide in an ACC codon D) a substitution of the first nucleotide of a GGG codon E) an insertion of a codon

B

Which small-scale mutation would be most likely to have a catastrophic effect on the functioning of a protein? A) a base substitution B) a base deletion near the start of a gene C) a base deletion near the end of the coding sequence, but not in the terminator codon D) deletion of three bases near the start of the coding sequence, but not in the initiator codon E) a base insertion near the end of the coding sequence, but not in the terminator codon

D

Why might a point mutation in DNA make a difference in the level of protein's activity? A) It might result in a chromosomal translocation. B) It might exchange one stop codon for another stop codon. C) It might exchange one serine codon for a different serine codon. D) It might substitute an amino acid in the active site. E) It might substitute the N-terminus of the polypeptide for the C-terminus.