ch 17 practice problems
Figure 17.2
(Image not found) It is an image of a tRNA molecule
37) A mutation in which of the following parts of a gene is likely to be most damaging to a cell? A) intron B) exon C) 5' UTR D) 3' UTR E) All would be equally damaging.
B Topic: Concept 17.3 Skill: Comprehension
66) Which of the following is not related to ribosomal activity? A) A site B) spliceosome C) codon recognition D) peptide bond formation E) P site
B Topic: Concept 17.4 Skill: Comprehension
72) Which of the above is analogous to a frameshift mutation? A. THERATATETHECAT B. THETACATETHERAT C. THECATARETHERAT D. THECATATTHERAT E. CATATETHERAT
D Topic: Concept 17.7 Skill: Application
80) Spliceosomes are composed of A) snRNPs and other proteins. B) polymerases and ligases. C) introns and exons. D) the RNA transcript and protein. E) snRNPs and snurps.
A Topic: Web/CD Activity: RNA Processing
81) Translation occurs in A) the cytoplasm. B) a lysosome. C) the nucleus. D) a mitochondrion. E) a nucleoplasm.
A Topic: Web/CD Activity: RNA Processing
82) What enzyme catalyzes the attachment of an amino acid to tRNA? A) aminoacyl-tRNA synthetase B) rubisco C) dextrinase D) argininosuccinate lyase E) nuclease
A Topic: Web/CD Activity: Translation
55) From the following list, which is the first event 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) Both B and D occur simultaneously.
B Topic: Concept 17.4 Skill: Knowledge
56) Choose the answer that has these events of protein synthesis in the proper sequence. 1. An aminoacyl-tRNA binds to the A site. 2. A peptide bond forms between the new amino acid and a polypeptide chain. 3. tRNA leaves the P site, and the P site remains vacant. 4. A small ribosomal subunit binds with mRNA. 5. tRNA translocates to the P site. A) 1, 3, 2, 4, 5 B) 4, 1, 2, 5, 3 C) 5, 4, 3, 2, 1 D) 4, 1, 3, 2, 5 E) 2, 4, 5, 1, 3
B Topic: Concept 17.4 Skill: Knowledge
15) What amino acid sequence will be generated, based on the following mRNA codon sequence? 5'AUG-UCU-UCG-UUA-UCC-UUG A) met-arg-glu-arg-glu-arg B) met-glu-arg-arg-gln-leu C) met-ser-leu-ser-leu-ser D) met-ser-ser-leu-ser-leu E) met-leu-phe-arg-glu-glu
D Topic: Concept 17.1 Skill: Application
18) Suppose the following DNA sequence was mutated from 3' AGAGAGAGAGAGAGAGAG 5' to 3' AGAAGAGAGATCGAGAGA 5'. What amino acid sequence will be generated based on this mutated DNA? A) arg-glu-arg-glu-arg-glu B) glu-arg-glu-leu-leu-leu C) ser-leu-ser-leu-ser-leu D) ser-ser-leu E) leu-phe-arg-glu-glu-glu
D Topic: Concept 17.1 Skill: Application
91) Which of the following mutations would be most likely to have a harmful effect on an organism? A) a base-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
E
4) If A, B, and C are all required for growth, a strain that is mutant for the gene encoding enzyme A would be able to grow on which of the following media? A) minimal medium B) minimal medium supplemented with nutrient "A" C) minimal medium supplemented with nutrient "B" D) minimal medium supplemented with nutrient "C" E) Answers C and D are correct.
E Topic: Concept 17.1 Skill: Application
Figure 17.1
(Image not found): it is a table of all the codons to the protein they make
Figure 17.1
(Image still not found) This is the same image of the table of codons to the protein
33) What are the coding segments of a stretch of eukaryotic DNA called? A) introns B) exons C) codons D) replicons E) transposons
B Topic: Concept 17.3 Skill: Knowledge
61) Which of the following does not occur during the termination phase of translation? A) A termination codon causes the A site to accept a release factor. B) The newly formed polypeptide is released. C) A tRNA with the next amino acid enters the P site. D) The two ribosomal subunits separate. E) Translation stops.
C Topic: Concept 17.4 Skill: Knowledge
3) A mutation results in a defective enzyme A. Which of the following would be a consequence of that mutation? A) an accumulation of A and no production of B and C B) an accumulation of A and B and no production of C C) an accumulation of B and no production of A and C D) an accumulation of B and C and no production of A E) an accumulation of C and no production of A and B
A Topic: Concept 17.1 Skill: Comprehension
27) Which of the following is least related to the other items? A) translation B) TATA box C) transcription D) template strand E) RNA polymerase II
A Topic: Concept 17.2 Skill: Comprehension
35) Once transcribed, eukaryotic mRNA typically undergoes substantial alteration that includes A) excision of introns. B) fusion into circular forms known as plasmids. C) linkage to histone molecules. D) union with ribosomes. E) fusion with other newly transcribed mRNA.
A Topic: Concept 17.3 Skill: Knowledge
39) During splicing, which molecular component of the spliceosome catalyzes the excision reaction? A) RNA B) DNA C) protein D) lipid E) sugar
A Topic: Concept 17.3 Skill: Knowledge
41) Which of the following is least related to the other items? A) snRNP B) triplet code C) wobble D) tRNA E) anticodon
A Topic: Concept 17.4 Skill: Comprehension
57) Which of the following is not directly involved in the process of translation? A) ligase B) tRNA C) rRNA D) mRNA E) aminoacyl-tRNA synthetase
A Topic: Concept 17.4 Skill: Knowledge
74) Sickle-cell disease is probably the result of which kind of mutation? A) point B) frameshift C) nonsense D) nondisjunction E) both B and D
A Topic: Concept 17.7 Skill: Application
70) Of the following types of mutations, which one is likely to be the most common? A) point mutation B) missense mutation C) base-pair substitution D) nonsense mutation E) frameshift mutation
A Topic: Concept 17.7 Skill: Comprehension
76) 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
A Topic: Concept 17.7 Skill: Comprehension
84) 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.
B
10) If proteins were composed of only 12 different kinds of amino acids, what would be the smallest possible codon size in a genetic system with four different nucleotides? A) 1 B) 2 C) 3 D) 4 E) 12
B Topic: Concept 17.1 Skill: Application
20) A codon A) consists of two nucleotides. B) may code for the same amino acid as another codon. C) consists of discrete amino acid regions. D) catalyzes RNA synthesis. E) is found in all eukaryotes, but not in prokaryotes.
B Topic: Concept 17.1 Skill: Knowledge
28) Which of the following statements best describes the termination of transcription in prokaryotes? A) RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase. B) RNA polymerase transcribes through the terminator sequence, causing the polymerase to fall off the DNA and release the transcript. C) RNA polymerase transcribes through an intron, and the snRNPs cause the polymerase to let go of the transcript. D) Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome. E) RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.
B Topic: Concept 17.2 Skill: Knowledge
49) A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of a 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 above will occur; the cell will recognize the error and destroy the tRNA.
B Topic: Concept 17.4 Skill: Application
45) What is an anticodon part of? A) DNA B) tRNA C) mRNA D) a ribosome E) an activating enzyme
B Topic: Concept 17.4 Skill: Knowledge
83) Base-pair substitutions involving the third base of a codon are unlikely to result in an error in the polypeptide. This is because A) substitutions are corrected before transcription begins. B) substitutions are restricted to introns. C) the base-pairing rules are less strict for the third base of codons and anticodons. D) a signal-recognition particle corrects coding errors. E) transcribed errors attract snRNPs, which then stimulate splicing and correction.
C
89) Which of the following is true of translation in both prokaryotes and eukaryotes? A) Translation is coupled to transcription. B) The product of transcription is immediately ready for translation. C) The codon UUU codes for phenylalanine. D) Ribosomes are affected by streptomycin. E) The signal-recognition particle (SRP) binds to the first 20 amino acids of certain polypeptides.
C
11) An extraterrestrial life form is discovered. It has a genetic code much like that of organisms on Earth except that there are five different DNA bases instead of four and the base sequences are translated as doublets instead of triplets. How many different amino acids could be accommodated by this genetic code? A) 5 B) 10 C) 25 D) 64 E) 32
C Topic: Concept 17.1 Skill: Application
12) The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer. You add polynucleotide phosphorylase to a solution of adenosine triphosphate and guanosine triphosphate. The resulting artificial mRNA molecule would have ________ possible different codons if the code involved two-base sequences and ________ possible different codons if the code involved three-base sequences. A) 2; 3 B) 2; 4 C) 4; 8 D) 4; 16 E) 16; 64
C Topic: Concept 17.1 Skill: Application
16) 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 codes 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
C Topic: Concept 17.1 Skill: Application
2) According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway? A) 0 B) 1 C) 2 D) 3 E) It cannot be determined from the pathway.
C Topic: Concept 17.1 Skill: Comprehension
22) The genetic code is essentially the same for all organisms. From this, one can logically assume all of the following except A) a gene from an organism could theoretically be expressed by any other organism. B) all organisms have a common ancestor. C) DNA was the first genetic material. D) the same codons in different organisms usually translate into the same amino acids. E) different organisms have the same number of different types of amino acids.
C Topic: Concept 17.1 Skill: Comprehension
8) The nitrogenous base adenine is found in all members of which group? A) proteins, triglycerides, and testosterone B) proteins, ATP, and DNA C) ATP, RNA, and DNA D) alpha glucose, ATP, and DNA E) proteins, carbohydrates, and ATP
C Topic: Concept 17.1 Skill: Knowledge
23) Which of the following is true for both prokaryotic and eukaryotic gene expression? A) After transcription, a 3' poly-A tail and a 5' cap are added to mRNA. B) Translation of mRNA can begin before transcription is complete. C) RNA polymerase binds to the promoter region to begin transcription. D) mRNA is synthesized in the 3' → 5' direction. E) The mRNA transcript is the exact complement of the gene from which it was copied.
C Topic: Concept 17.2 Skill: Knowledge
30) All of the following are found in prokaryotic mRNA except A) the AUG codon. B) the UGA codon. C) introns. D) uracil. E) cytosine.
C Topic: Concept 17.2 Skill: Knowledge
43) 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 Topic: Concept 17.4 Skill: Application
47) 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
C Topic: Concept 17.4 Skill: Knowledge
51) What are ribosomes composed of? A) rRNA only B) proteins only C) both rRNA and protein D) mRNA, rRNA, and protein E) mRNA, tRNA, rRNA, and protein
C Topic: Concept 17.4 Skill: Knowledge
52) Where is eukaryotic ribosomal RNA transcribed? A) the Golgi apparatus B) ribosomes C) the nucleolus D) X chromosomes E) prokaryotic cells only
C Topic: Concept 17.4 Skill: Knowledge
53) What is the most abundant type of RNA? A) mRNA B) tRNA C) rRNA D) pre-mRNA E) hnRNA
C Topic: Concept 17.4 Skill: Knowledge
73) Which of the above is analogous to a single substitution mutation? A. THERATATETHECAT B. THETACATETHERAT C. THECATARETHERAT D. THECATATTHERAT E. CATATETHERAT
C Topic: Concept 17.7 Skill: Application
71) 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 stop codon into the mRNA. D) It alters the reading frame of the mRNA. E) It prevents introns from being expressed.
C Topic: Concept 17.7 Skill: Knowledge
85) 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 does. 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.
D
86) The metabolic pathway of arginine synthesis is as follows: Precursor Ornithine Citrulline Arginine A B C Beadle and Tatum discovered several classes of Neurospora mutants that were able to grow on minimal medium with arginine added. Class I mutants were also able to grow on medium supplemented with either ornithine or citrulline, whereas class II mutants could grow on citrulline medium but not on ornithine medium. From the behavior of their mutants, Beadle and Tatum were able to conclude that A) one gene codes for the entire metabolic pathway. B) the genetic code of DNA is a triplet code. C) class I mutants have their mutations later in the nucleotide chain than do class II mutants. D) class I mutants have a nonfunctional enzyme at step A, and class II mutants have one at step B. E) class III mutants have nonfunctional enzymes for all three steps.
D
90) Using the genetic code in Figure 17.1, identify a 5' → 3' sequence of nucleotides in the DNA template strand for an mRNA coding for the polypeptide sequence Phe-Pro-Lys. A) UUU-GGG-AAA B) GAA-CCC-CTT C) AAA-ACC-TTT D) CTT-CGG-GAA E) AAA-CCC-UUU
D
13) A particular triplet of bases in the template strand of DNA is AGT. The corresponding codon for the mRNA transcribed is A) AGT. B) UGA. C) TCA. D) ACU. E) either UCA or TCA, depending on wobble in the first base
D Topic: Concept 17.1 Skill: Application
19) A particular eukaryotic protein is 300 amino acids long. Which of the following could be the maximum number of nucleotides in the DNA template strand that codes for the amino acids in this protein? A) 3 B) 100 C) 300 D) 900 E) 1,800
D Topic: Concept 17.1 Skill: Application
5) If A, B, and C are all required for growth, a strain mutant for the gene encoding enzyme B would be capable of growing on which of the following media? A) minimal medium B) minimal medium supplemented with "A" C) minimal medium supplemented with "B" D) minimal medium supplemented with "C" E) answers B and C
D Topic: Concept 17.1 Skill: Application
9) Using RNA as a template for protein synthesis instead of translating proteins directly from the DNA is advantageous for the cell because A) RNA is much more stable than DNA. B) RNA acts as an expendable copy of the genetic material, allowing the DNA to serve as a permanent, pristine repository of the genetic material. C) many mRNA molecules can be transcribed from a single gene, increasing the potential rate of gene expression. D) B and C only E) A, B, and C
D Topic: Concept 17.1 Skill: Comprehension
7) Which of the following represents a similarity between RNA and DNA? A) Both are double-stranded. B) the presence of uracil C) the presence of an OH group on the 2' carbon of the sugar D) nucleotides consisting of a phosphate, sugar, and nitrogenous base E) Both are found exclusively in the nucleus.
D Topic: Concept 17.1 Skill: Comprehension
24) Which of the following are transcribed from DNA? A) protein B) exons C) rRNA D) B and C only E) A, B, and C
D Topic: Concept 17.2 Skill: Application
25) RNA polymerase and DNA polymerase differ in that A) RNA polymerase uses RNA as a template, and DNA polymerase uses a DNA template. B) RNA polymerase binds to single-stranded DNA, and DNA polymerase binds to double-stranded DNA. C) RNA polymerase is much more accurate than DNA polymerase. D) RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to initiate DNA synthesis. E) RNA polymerase does not need to separate the two strands of DNA in order to synthesize an RNA copy, whereas DNA polymerase must unwind the double helix before it can replicate the DNA.
D Topic: Concept 17.2 Skill: Comprehension
26) Which of the following is not a part of the eukaryotic transcription initiation complex? A) promoter B) RNA polymerase C) transcription factors D) snRNP E) TATA box
D Topic: Concept 17.2 Skill: Knowledge
40) Alternative RNA splicing A) is a mechanism for increasing the rate of transcription. B) can allow the production of proteins of dramatically different sizes from a single mRNA. C) can allow the production of proteins of dramatically different amino acid sequences from a single mRNA. D) B and C only E) A, B, and C
D Topic: Concept 17.3 Skill: Knowledge
48) Figure 17.2 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) UUC E) CAU
D Topic: Concept 17.4 Skill: Application
50) 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 two 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) A and B only E) A, B, and C
D Topic: Concept 17.4 Skill: Comprehension
65) Which of the following is least related to the other items? A) exons B) introns C) RNA splicing D) signal-recognition particles (SRPs) E) mRNA
D Topic: Concept 17.4 Skill: Comprehension
42) All of the following are directly involved in translation except A) mRNA. B) tRNA. C) ribosomes. D) DNA. E) aminoacyl-tRNA synthetase enzymes.
D Topic: Concept 17.4 Skill: Knowledge
59) During translation, chain elongation continues until what happens? A) No further amino acids are needed by the cell. B) All tRNAs are empty. C) The polypeptide is long enough. D) A stop codon is encountered. E) The ribosomes run off the end of mRNA.
D Topic: Concept 17.4 Skill: Knowledge
63) What is one 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 Topic: Concept 17.4 Skill: Knowledge
68) Which of the following is (are) true about RNA? A) snoRNA aids in processing pre-rRNA transcripts in the nucleolus. B) SRP RNA is an essential component of spliceosomes. C) It has functional groups that allow it to act as a catalyst (ribozyme). D) Only A and C are true. E) A, B, and C are true.
D Topic: Concept 17.5 Skill: Comprehension
14) 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 Topic: Concept 17.1 Skill: Application
17) What is the sequence of a peptide based on the mRNA sequence 5' UUUUCUUAUUGUCUU 3' ? A) leu-cys-tyr-ser-phe B) cyc-phe-tyr-cys-leu C) phe-leu-ile-met-val D) leu-pro-asp-lys-gly E) phe-ser-tyr-cys-leu
E Topic: Concept 17.1 Skill: Application
21) If the triplet CCC codes for the amino acid proline in bacteria, then in plants CCC should code for A) leucine. B) valine. C) cystine. D) phenylalanine. E) proline.
E Topic: Concept 17.1 Skill: Comprehension
6) We now know that the one gene-one enzyme hypothesis is not entirely accurate because A) many genes code for proteins that are not enzymes. B) a single gene codes for a single polypeptide chain, and many enzymes are made up of more than one polypeptide chain. C) many genes code for RNA molecules that have no enzymatic activity. D) A and B only E) A, B, and C
E Topic: Concept 17.1 Skill: Comprehension
31) Which of the following helps to stabilize mRNA by inhibiting its degradation? A) TATA box B) spliceosomes C) 5' cap D) poly-A tail E) both C and D
E Topic: Concept 17.3 Skill: Knowledge
38) Which of the following is (are) true of snRNPs? A) They are made up of both protein and RNA. B) They bind to splice sites at each end of the intron. C) They join together to form a large structure called the spliceosome. D) Only A and C are true. E) A, B, and C are true
E Topic: Concept 17.3 Skill: Knowledge
44) Accuracy in the translation of mRNA into the primary structure of a protein 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) both C and D
E Topic: Concept 17.4 Skill: Comprehension
60) As a ribosome translocates along an mRNA molecule by one codon, which of the following occurs? A) The tRNA that was in the A site moves into the P site. B) The tRNA that was in the P site moves into the A site. C) The tRNA that was in the P site moves to the E site and is released. D) The tRNA that was in the A site departs from the ribosome. E) Both A and C are correct.
E Topic: Concept 17.4 Skill: Knowledge
54) The function of the ribosome in polypeptide synthesis is to A) hold mRNA and tRNAs together. B) catalyze the addition of amino acids from tRNAs to the growing polypeptide chain. C) move along the mRNA and eject tRNAs during the translocation process. D) A and B only E) A, B, and C
E Topic: Concept 17.4 Skill: Knowledge
87) 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.
A
88) 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.
A
1) Garrod hypothesized that "inborn errors of metabolism" such as alkaptonuria occur because A) genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes. B) enzymes are made of DNA, and affected individuals lack DNA polymerase. C) many metabolic enzymes use DNA as a cofactor, and affected individuals have mutations that prevent their enzymes from interacting efficiently with DNA. D) certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors. E) metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies.
A Topic: Concept 17.1 Skill: Knowledge
34) A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of 400 amino acids. This is best explained by the fact that A) many noncoding nucleotides are present in mRNA. B) there is redundancy and ambiguity in the genetic code. C) many nucleotides are needed to code for each amino acid. D) nucleotides break off and are lost during the transcription process. E) there are termination exons near the beginning of mRNA.
A Topic: Concept 17.3 Skill: Comprehension
36) Introns are significant to biological evolution because A) their presence allows exons to be moved around more easily, creating proteins with new combinations of functional domains. B) they protect the mRNA from degeneration. C) they are translated into essential amino acids. D) they maintain the genetic code by preventing incorrect DNA base pairings. E) they correct enzymatic alterations of DNA bases.
A Topic: Concept 17.3 Skill: Comprehension
62) What are polyribosomes? A) groups of ribosomes reading a single mRNA simultaneously B) ribosomes containing more than two subunits C) multiple copies of ribosomes associated with giant chromosomes D) aggregations of vesicles containing ribosomal RNA E) ribosomes associated with more than one tRNA
A Topic: Concept 17.4 Skill: Knowledge
69) Which of the following statements are true about protein synthesis in prokaryotes? A) Translation can begin while transcription is still in progress. B) Extensive RNA processing is required before prokaryotic transcripts can be translated. C) Prokaryotic cells have complicated mechanisms for targeting proteins to the appropriate cellular organelles. D) Only A and B are true. E) A, B, and C are true.
A Topic: Concept 17.6 Skill: Comprehension
92) Which component is not directly involved in translation? A) mRNA B) DNA C) tRNA D) ribosomes E) GTP
B
29) RNA polymerase moves along the template strand of DNA in the ________ direction, and adds nucleotides to the ________ end of the growing transcript. A) 3' to 5'; 5' B) 3' to 5'; 3' C) 5' to 3'; 5' D) 5' to 3'; 3'
B Topic: Concept 17.2 Skill: Comprehension
32) What is a ribozyme? A) An enzyme that uses RNA as a substrate B) An enzyme made up of RNA 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
B Topic: Concept 17.3 Skill: Knowledge
46) A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The following activated 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. (Image not found) The dipeptide that will form will be A) cysteine-alanine. B) proline-threonine. C) glycine-cysteine. D) alanine-alanine. E) threonine-glycine.
B Topic: Concept 17.4 Skill: Application
64) 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 Topic: Concept 17.4 Skill: Knowledge
67) When does translation begin in prokaryotic cells? A) after a transcription initiation complex has been formed B) during transcription C) after the 5' caps are converted to mRNA D) once the pre-mRNA has been converted to mRNA E) as soon as the DNA introns are removed from the template
B Topic: Concept 17.4 Skill: Knowledge
77) Which point 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
B Topic: Concept 17.7 Skill: Comprehension
79) During RNA processing a(n) ________ is added to the 3' end of the RNA. A) 3' untranslated region B) a long string of adenine nucleotides C) 5' untranslated region D) coding segment E) modified guanine nucleotide
B Topic: Web/CD Activity: RNA Processing
78) Which of these correctly illustrates the pairing of DNA and RNA nucleotides? A) GTTACG with CAATCG B) GTTACG with CAAUGC C) GTTACG with GTTACG D) GTTACG with ACCGTA E) GTTACG with UAACAU
B Topic: Web/CD Activity: Transcription
58) Which of the following components are present upon the completion of translation initiation? A) small ribosomal subunit B) large ribosomal subunit C) initiator tRNA D) A and C only E) A, B, and C
E Topic: Concept 17.4 Skill: Knowledge
75) 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.
E Topic: Concept 17.7 Skill: Comprehension