Ch. 12 Gene Expression at a Molecular Level Study Questions and Answers

58) When does the small ribosomal subunit binds to the translational complex in eukaryotic cells? A) It is the first component to bind to the mRNA. B) After the initiator tRNA binds, but before the start codon has been found. C) After the large ribosomal subunit binds, but before the initiator tRNA binds. D) After the start codon has been found by initiator tRNA. E) The small ribosomal subunit binds the initiator tRNA and this complex is the first to bind to the mRNA.

A) It is the first component to bind to the mRNA.

23) Which of the following statements about the 5′cap and mRNA processing is TRUE? A) The addition of a 5′ cap to mRNA occurs while the pre-mRNA is being made. B) The 5' cap causes the mRNA to be rapidly degraded. C) The 5' cap prevents the exit of mRNA from the nucleus. D) The 5′ cap is added to the pre-mRNA by spliceosomes. E) The 5′ cap is a group of adenosine molecules.

A) The addition of a 5' cap to mRNA occurs while the pre-mRNA is being made.

22) Which of the following statements about RNA processing in eukaryotes is INCORRECT? A) The excision of introns from pre-mRNA is the only modification required to produce a mature mRNA. B) A protein/RNA complex is used to remove introns from the pre-mRNA. C) A poly A tail is added on to the 3′ end of the mRNA. D) A 7-methylguanosine cap is added on to the 5′end of the mRNA. E) Modification occurs in the nucleus.

A) The excision of introns from pre-mRNA is the only modification required to produce a mature mRNA.

2) Wild type bread mold can grow in a minimal medium without supplements, while certain mutated strains can only grow in a minimal medium that is supplemented with specific intermediates found in the following metabolic pathway for arginine synthesis. See the figure below for an overview of the arginine biosynthetic pathway. A strain that can grow in minimal medium containing ornithine, citrulline, or arginine, but not in minimal medium alone would have a mutation in the gene that encodes for A) enzyme 1. B) enzymes 1, 2, and 3. C) enzyme 2. D) The strain would be the wild type with no genetic mutations. E) enzyme 3.

A) enzyme 1.

61) Which of the following antibiotics inhibit translation by blocking the elongation stage? (Select all that apply) A) erythromycin B) tetracycline C) streptomycin D) puromycin E) chloramphenicol

A) erythromycin B) tetracycline E) chloramphenicol

14) Transcription begins near a site in the DNA called the A) promoter B) enhancer C) response element D) transcription unit E) regulatory sequence

A) promoter

3) The process that produces mRNA from DNA is called A) transcription. B) translation. C) replication. D) processing. E) post-translational modifications.

A) transcription.

47) A defective ribosome would have the MOST detrimental effect on A) translation. B) replication. C) transcription. D) replication and transcription. E) replication and translation.

A) translation.

34) Identify the anticodon sequences for an mRNA sequence that is 5′-AUG GGC ACU CAU-3′. A) 3′AUG 5' - 3' GGC 5' - 3' ACU 5' - 3' CAU5′ B) 3′UAC 5' - 3' CCG 5' - 3' UGA 5' - 3' GUA5′ C) 5′AUG 3' - 5' GGC 3' - 5' ACU 3' - 5' CAU3′ D) 5′UAC 3' - 5' CCG 3' - 5' UGA 3' - 5' GUA3′ E) 3′TAC 5' - 3' CCG 5' -5' TGA 3' - 5' GTA 3′

B) 3' UAC 5' - 3' CCG 5' - 3' UGA 5' - 3' GUA 5'

44) What molecule indirectly provides the energy for translation? A) ADP B) ATP C) GMP D) GDP E) GTP

B) ATP

50) Which of the following statements describe a reason ribosomal genes are useful for comparing evolutionary relationships among organisms? A) There are many differences in these genes, even among closely related species. B) All organisms possess these genes and they can be compared with each other. C) These are the only genes that have been sequenced for every organism on Earth. D) Ribosomes of prokaryotes and eukaryotes are identical. E) It is possible to compare the large subunit genes with the small subunit genes.

B) All organisms possess these genes and they can be compared with each other.

18) What protein is involved in synthesizing messenger RNA in eukaryotes? A) RNA polymerase I B) RNA polymerase II C) RNA polymerase III D) sigma factor E) both RNA polymerase I and III

B) RNA polymerase II

5) ________ is to transcription as ________ are to translation. A) RNA spliceosome; ribosomes B) RNA polymerase; ribosomes C) RNA polymerase; RNA spliceosomes D) DNA polymerase; RNA polymerase E) DNA polymerase; ribosomes

B) RNA polymerase; ribosomes

30) Which of the following statements about the mRNA start codon is INCORRECT? A) The start codon is only a few nucleotides from the ribosomal binding site. B) The start codon is usually GGA. C) The start codon is usually AUG. D) The start codon specifies the amino acid methionine. E) The start codon defines the reading frame.

B) The start codon is usually GGA.

26) Intervening sequences that are transcribed, but not translated into protein are called A) exons. B) introns. C) spliceosomes. D) transposons. E) transcription factors.

B) introns.

52) The amino acids of a growing polypeptide chain are held together by what kind of bond during the elongation stage of translation? A) hydrogen B) peptide C) glycosidic D) noncovalent E) lactose

B) peptide

8) The transcription process in a eukaryotic gene directly produces A) rRNA B) pre-mRNA C) mRNA D) DNA E) Protein

B) pre-mRNA

51) What factors are utilized by the cell in order to recognize the stop codon and disassemble the translation machinery? A) elongation factors B) release factors C) transcription factors D) initiation factors E) mRNA factors

B) release factors

31) How many nucleotides are contained in a single codon? A) one B) three C) four D) six E) nine

B) three

12) Which region of a structural gene contains the information that specifies an amino acid sequence? A) promoter region B) transcribed region C) terminator D) regulatory sequence E) enhancer region

B) transcribed region

45) How many distinct aminoacyl-tRNA synthetases does each cell make? A) ~1 B) ~20 C) ~60 D) ~120 E) ~180

B) ~20

17) If a DNA template strand has a sequence of 3′ TACAATGTAGCC 5′, the RNA produced from it will be which sequence? A) 3′TACAATGTAGCC5′ B) 5′ATGTTACATCGG3′ C) 5′AUGUUACAUCGG3' D) 3′AUGUUACAUCGG5′ E) 3′ATGTTACATCGG5′

C) 5' AUGUUACAUCGG 3'

33) The following mRNA transcript would result in which polypeptide sequence? 5′-ACU UUC ACU AUG UUU UUA UCC UCC ACU CCU UGA-3′ Use the following codons and the amino acids they encode. AUG = Start or Met; UUU, UUC = Phe; UUA, UUG = Leu; UCU, UCC = Ser; CCU, CCC = Pro; ACU, ACC = Thr; UGA = Stop. A) Thr-Phe-Thr B) Phe-Leu-Ser-Ser-Thr-Pro C) Met-Phe-Leu-Ser-Ser-Thr-Pro D) Thr-Phe-Thr-Phe-Leu-Ser-Ser-Thr-Pro E) Met-Phe-Leu-Ser-Ser

C) Met-Phe-Leu-Ser-Ser-Thr-Pro

24) What is the function of the poly A tail? A) The poly A tail is required for the termination of translation, it is recognized by the release factor proteins B) The poly A tail is required for the mRNA to resume its double helical structure C) The poly A tail increases mRNA stability in eukaryotes. D) The poly A tail increases mRNA stability in prokaryotes. E) The poly A tail serves as a termination sequence for RNA polymerase III.

C) The poly A tail increases mRNA stability in eukaryotes.

36) If Nirenberg and Leder had the technology, what would be a better substitute to using radiolabeled amino acids? A) radiolabeled proteins B) radiolabeled tRNAs C) amino acids labeled with a fluorescent dye D) All of the answers are correct.

C) amino acids labeled with a fluorescent dye

53) The term N-terminus refers to the presence of a(n) ________ at one of the ends of a polypeptide. A) oxygen atom B) carboxyl group C) amino group D) carbonyl group E) sulfate group

C) amino group

42) What enzyme catalyzes the attachment of amino acids to tRNA molecules? A) helicase B) topoisomerase C) aminoacyl-tRNA synthetase D) ribosome E) translation factor

C) aminoacyl-tRNA synthetase

59) Translation occurs in the ________ of bacteria and in the ________ of eukaryotic cells. A) nucleus; cytoplasm B) cytosol; endoplasmic reticulum C) cytoplasm; cytosol D) cytoplasm; nucleus E) nucleus; nucleus

C) cytoplasm; cytosol

49) The most common eukaryotic ribosome carries out its function in the A) Golgi apparatus. B) nucleus. C) cytosol. D) mitochondria. E) chloroplast.

C) cytosol.

1) Wild type bread mold can grow in a minimal medium without supplements, while certain mutated strains can only grow in a minimal medium that is supplemented with specific intermediates. See the figure below for an overview of the arginine biosynthetic pathway. A strain that can grow in a minimal medium containing arginine, but NOT in minimal media containing citrulline nor in minimal media containing ornithine would have a mutation in the gene that encodes for ________. A) enzyme 1. B) enzyme 2. C) enzyme 3. D) both enzymes 1 and 3. E) both enzymes 2 and 3.

C) enzyme 3.

41) An mRNA sequence is 5′-AUG GGC ACU CAU ACU UAA-3′, where AUG is the start codon and UAA is the stop codon. How many distinct aminoacyl-tRNA synthetases are required to translate the mRNA sequence? A) two B) three C) four D) five E) six

C) four

37) Which of the following serves as the "translator" or intermediary between an mRNA codon and an amino acid? A) rRNA B) snRNA C) tRNAterm-37 D) siRNA E) snRNPs

C) tRNAterm-37

19) What protein influences the ability of RNA polymerase to transcribe genes? A) DNA polymerases B) DNA helicases C) transcription factors D) snRNPs E) tRNA

C) transcription factors

54) Which sequence of events CORRECTLY describes the initiation and elongation steps of translation in prokaryotic cells? (1) initiator tRNA binds start codon on mRNA (2) small ribosomal subunit binds to mRNA (3) large ribosomal subunit binds (4) tRNA entry and peptidyl transfer reaction (5) translocation of ribosome and release of tRNA A) 1, 2, 3, 4, 5 B) 1, 2, 3, 5, 4 C) 1, 3, 2, 4, 5 D) 2, 3, 1, 5, 4 E) 2, 1, 3, 4, 5

E) 2, 1, 3, 4, 5

43) When an aminoacyl-tRNA synthetase charges a tRNA, which molecule is released? A) mRNA B) ATP C) AMP D) pyrophosphate E) AMP and pyrophosphate

E) AMP and pyrophosphate

27) If a cell's spliceosomes were mutated so they no longer functioned normally, what consequences would result? A) Introns would remain in the mature mRNA. B) Exons would be missing in the mature mRNA. C) Transcription would cease. D) A functional protein would still be produced. E) RNA processing would remain intact.

A) Introns would remain in the mature mRNA.

56) Translation is a relatively slow process.

False

7) All enzymes are proteins.

False

48) In eukaryotes, the 40S and 60S subunits combine to form a 100S ribosome.

False

40) Which of the following statements about tRNA is FALSE? A) tRNAs of both eukaryotes and prokaryotes share common features. B) The two-dimensional structure of tRNAs exhibits a cloverleaf pattern. C) tRNAs are produced in the nucleus. D) Functional tRNAs have been spliced by spliceosomes. E) tRNAs possess an anticodon complementary to the codon.

D) Functional tRNAs have been spliced by spliceosomes.

15) Which of the following statements about RNA polymerase in bacteria is INCORRECT? A) It binds the promoter region of a gene. B) It is bound to a sigma factor during initiation of transcription. C) It synthesizes RNA. D) It catalyzes the addition of nucleotides to the 5′end of a growing RNA strand. E) It dissociates from the DNA at the terminator.

D) It catalyzes the addition of nucleotides to the 5' end of a growing RNA strand.

21) What basic features of transcription is NOT shared by both prokaryotes and eukaryotes? A) Both prokaryotic and eukaryotic genes have a promoter site. B) RNA polymerase transcribes genes in both prokaryotes and eukaryotes. C) Gene transcription involves initiation, elongation, and termination in both prokaryotes and eukaryotes. D) The complexity of protein components involved in transcription is similar for both prokaryotes and eukaryotes. E) The initiation of transcription in both prokaryotes and eukaryotes involves the interactions of more than one protein.

D) The complexity of protein components involved in transcription is similar for both prokaryotes and eukaryotes.

60) What is the major difference in the termination stage of translation between prokaryotes and eukaryotes? A) There is no stop codon in prokaryotes while a stop codon is necessary in eukaryotes. B) Ribosomal subunits dissociate in prokaryotes, but remain intact in eukaryotes. C) mRNA remains connected to the small ribosomal subunit (30S) in prokaryotes, but is released from the small ribosomal subunit (40S) in eukaryotes. D) There are two termination factors in prokaryotes (RF1 and RF2) and only one factor in eukaryotes (eRF). E) There is one stop codon in prokaryotes (UAG) and three in eukaryotes (UAA, UAG, UGA).

D) There are two termination factors in prokaryotes (RF1 and RF2) and only one factor in eukaryotes (eRF).

28) What process enables a single gene to encode two or more polypeptides that are different in their amino acid sequence? A) reverse transcription B) self-splicing C) capping D) alternative splicing E) regulatory splicing

D) alternative splicing

29) Because more than one codon can specify the same amino acid, the genetic code is said to be A) repetitive. B) redundant. C) reverse. D) degenerate. E) wobbly.

D) degenerate.

9) An organized unit of DNA sequences that enables a segment of DNA to be transcribed into RNA and ultimately results in the formation of a functional product is called a ________. A) chromosome B) trait C) allele D) gene E) expression

D) gene

25) What molecule(s) exhibits self-splicing? A) rRNA B) tRNA C) mRNA D) rRNA and tRNA E) rRNA and mRNA

D) rRNA and tRNA

11) What products of nonstructural genes are never translated? A) transfer RNA B) ribosomal RNA C) messenger RNA D) transfer RNA and ribosomal RNA E) ribosomal RNA and messenger RNA

D) transfer RNA and ribosomal RNA

55) Because of the abundance of ribosomes, translation is NOT an energy costly process for the cell.

False

20) Which of the following statements accurately describes transcription by RNA polymerase? A) RNA polymerase simultaneously transcribe both strands of DNA B) It is possible for one RNA polymerase to transcribe one strand of DNA in the 5' to 3' direction and another RNA polymerase to transcribe the complementary strand of DNA in the 3' to 5' direction, producing two identical transcripts C) It is possible for one RNA polymerase to transcribe one strand of DNA in the 5' to 3' direction and another RNA polymerase to transcribe the complementary strand of DNA in the 5' to 3' direction, producing two identical transcripts D) It is possible for one RNA polymerase to transcribe one strand of DNA in the 5' to 3' direction and another RNA polymerase to transcribe the complementary strand of DNA in the 3' to 5' direction, producing two different transcripts E) It is possible for one RNA polymerase to transcribe one strand of DNA in the 5' to 3' direction and another RNA polymerase to transcribe the complementary strand of DNA in the 5' to 3' direction, producing two different transcripts

E) It is possible for one RNA polymerase to transcribe one strand of DNA in the 5' to 3' direction and another RNA polymerase to transcribe the complementary strand of DNA in the 5' to 3' direction, producing two different transcripts.

35) Which amino acid would Nirenberg and Leder have found when they used the triplet UAG? A) isoleucine B) proline C) lysine D) threonine E) None of the answers are correct.

E) None of the answers are correct.

4) The processes of transcription and translation are collectively known as A) RNA processing. B) gene duplication. C) protein synthesis. D) DNA synthesis. E) gene expression.

E) gene expression.

46) What is NOT a component of the translation machinery? A) mRNA B) tRNA C) translation factors D) ribosomes E) protein polymerase

E) protein polymerase

10) A single gene always encodes an enzyme

False

13) As part of the transcriptional unit, regulatory sequences are the sites where RNA polymerase and transcription factors bind to regulate transcription.

False

38) The cells of every organism make only a few different tRNA molecules encoded by the same gene.

False

39) tRNA contains the genetic code for producing a polypeptide.

False

16) RNA polymerase II of eukaryotes always requires more than one general transcription factor to initiate transcription.

True

32) More than one codon can specify the same amino acid.

True

57) The termination of translation occurs when a release factor recognizes the stop codon.

True

6) The molecule mRNA, which contains the information to make a polypeptide, is constructed from a DNA template.

True