Chapter 9
58. If the wild type DNA sequence reads THE CAT ATE THE BIG RAT, what type of mutation would change the sequence to THE CAT ATE (stop)? A. Missense B. Nonsense C. Insertion D. Deletion E. Silent
B
78. DNA replication proceeds in one direction around the bacterial chromosome. True False
False
81. Introns have no detectable functions. True False
False
83. Lactose is a corepressor in the lac operon. True False
False
85. Induced mutations are initiated by errors in DNA replication. True False
False
87. All mutations are not beneficial to the cell. True False
False
True / False Questions 76. The smallest unit of heredity is a chromosome. True False
False
True / False Questions 91. A bacterial cell has replicated its plasmid, and when this cell divides into 2 daughter cells, each cell receives one copy of the plasmid. This is an example of horizontal gene transfer. True False
False
59. A frameshift is caused by ______ mutations. A. missense and insertion B. missense and nonsense C. nonsense and deletion D. deletion and insertion E. insertion and nonsense
D
12. Each nucleotide is composed of A. one phosphate, one nitrogenous base, and one sugar. B. one phosphate, one nitrogenous base, and two sugars. C. two phosphates, one nitrogenous base, and one sugar. D. two phosphates, one nitrogenous base, and two sugars. E. one phosphate, two nitrogenous bases, and one sugar.
A
19. Okazaki fragments are attached to the growing end of the lagging strand by _______. A. DNA ligase B. DNA polymerase C. DNA helicase D. DNA gyrase E. primase
A
24. Helicase ______. A. unwinds DNA B. supercoils DNA C. unwinds RNA D. winds RNA
A
25. DNA Polymerase I A. removes primers. B. adds bases to new DNA chain. C. seals DNA gaps. D. proofreads DNA chain.
A
35. Which of the following is not a type of microRNA? A. tRNA B. miRNA C. Antisense RNA D. Riboswitch E. siRNA
A
36. All of the following pertain to transcription except A. it occurs on a ribosome in the cytoplasm. B. it occurs before translation. C. it requires RNA polymerase. D. it requires a template DNA strand. E. it is a process that contributes to the synthesis of protein.
A
37. The nontranscribed region of DNA to which RNA polymerase binds to initiate transcription is called the ________. A. promoter B. operator C. operon D. exon E. intron
A
41. The following pertain to ribosomes during protein synthesis exceptev: 11_02_2012 A. they contain codons within their rRNA molecules. B. they participate only in translation. C. they bind to the 5'end of mRNA by their small subunit. D. they use their large subunit to supply enzymes for peptide bonding. E. they shift towards the 3'direction along the mRNA strand from one codon to the next.
A
46. Which is incorrect about inducible operons? A. They have genes turned off by a buildup of end product. B. They are often for use in catabolic pathways. C. They are normally turned off. D. They are turned on by the substrate of the enzyme. E. They include the lac operon.
A
53. Repressible operons require that ______ binds to the repressor protein before it can bind to the operator. A. the product B. a cofactor C. a coenzyme D. the substrate E. the reactant
A
57. If the wild type DNA sequence reads THE CAT ATE THE BIG RAT, what type of mutation would change the sequence to THE CAT ATE THE BAG RAT? A. Point B. Nonsense C. Insertion D. Deletion E. Silent
A
60. What type of mutation alters the base but not the amino acid being coded for? A. Silent B. Back C. Point D. Nonsense E. Missense
A
9. Which is incorrect about purines? A. They are only found in DNA, not in RNA. B. They are nitrogenous bases. C. They are always paired with a specific pyrimidine. D. They include adenine and guanine. E. They are found within nucleotides.
A
90. A mutation has occurred during DNA replication while the cell was preparing to divide. As a result of this, the codon ACU of mRNA has now become ACC. Interestingly, there is no change to the protein being made. Why not? A. This is a silent mutation. B. The original amino acid isoleucine was changed to leucine, but they are the same variation of amino acid so no change to the protein. C. The mutation was fixed, and even though the codon is now ACC the correct amino acid is put into place for the normal protein. D. This is not a mutation that causes a big change, so there is no change to the protein being made.
A
98. The field of genomics refers to A. the study of an organism's complete genome, including plasmid, mitochondrial, and chloroplast DNA. B. the study of chromosomal DNA. C. the study of an organism's plasmids. D. the study of cellular, but not viral, genomes.
A
Multiple Choice Questions 88. An unidentified cell was found to contain introns and exons. It also expresses DNA polymerase and RNA polymerase. Although it exhibits a promoter region, it has no operons. You conclude that this cell A. is eukaryotic. B. is prokaryotic. C. is either a prokaryotic or eukaryotic cell. D. is actually a virus.
A
11. All of the following pertain to nitrogenous bases except A. they form pairs by hydrogen bonding. B. guanine pairs with uracil. C. adenine pairs with thymine. D. cytosine and thymine are pyrimidines. E. they allow variation from one nucleotide to another which creates the encoded information.
B
14. The duplication of a cell's DNA is called _______. A. mitosis B. replication C. transcription D. translation E. mutation
B
16. During replication, each parent DNA strand serves as a _____ for synthesis of new DNA strands. A. copy point B. template C. comparison molecule D. scaffold E. reservoir
B
18. DNA polymerase III A. is needed for adding nucleotides during mRNA synthesis. B. synthesizes new DNA only in the 5'to 3'direction. C. cannot add nucleotides to the lagging strand. D. synthesizes an RNA primer.
B
21. The enzyme that can proofread replicating DNA, detect incorrect bases, excise them, and correctly replace them is _______. A. DNA ligase B. DNA polymerase C. DNA helicase D. DNA gyrase E. primase
B
33. Which molecule is translated into an amino acid sequence? A. Ribosomal RNA B. Messenger RNA C. Transfer RNA D. Primer RNA E. Ribozymes
B
48. Synthesis of an inducible enzyme requires A. repressor alone bound to operator. B. substrate bound to repressor. C. substrate bound to promoter. D. corepressor and repressor binding to operator.
B
61. A screening system called the _______ test is used for detecting chemicals with carcinogenic potential. A. Koch B. Ames C. mutation D. cancer E. Iowa
B
62. The process in which mutations are removed and the correct bases added is called ________. A. transduction B. excision repair C. frameshift D. back-mutation E. transformation
B
63. Bacterial conjugation involves A. a bacteriophage carrying donor DNA to the recipient cell. B. a donor cell with a plasmid that synthesizes a pilus. C. naked DNA fragments from a lysed donor cell taken up by a recipient cell. D. new progeny cells with genes from two parent bacterial cells.
B
67. Hfr transfer involves all of the following except A. gene integration into the bacterial chromosome. B. independent plasmid transfer. C. F factor is part of the F+ donor chromosome. D. high frequency transfer. E. a pilus connection between F+ and F- cells.
B
70. A bacteriophage transfers a random fragment of DNA of the previous host to the current host. This is an example of A. conjugation. B. generalized transduction. C. specialized transduction. D. the creation of an Hfr cell.
B
71. The jumping of a gene from one location to another is done by ________. A. conjugation B. transposons C. transformation D. transduction E. transmission
B
89. Looking at your results of the Ames test using bacteriological agar medium plates lacking the amino acid histidine, you find that there are many colonies growing on the agar. How do you interpret this result? A. The bacterium has turned its operon genes on, producing proteins necessary for growth. B. The chemical being tested is mutagenic. C. The bacterium does not have any plasmids, so it cannot grow on the medium. D. The drug being tested has no inhibitory effect on the bacterium; therefore, it is not a good antibiotic to give for treatment of disease.
B
97. The fields of genomics and proteomics differ in that A. the field of genomics involves the study of DNA replication and the field of proteomics refers to the study of transcription and translation. B. genomics refers to the study of an organism's entire genome, whereas proteomics is the study of expressed proteins. C. genomics is the study of an organism's chromosomes and the resulting proteins are studied in the field of proteomics. D. genomics is the study of an organism's chromosomes and proteomics is the study of transcription and translation of proteins.
B
Multiple Choice Questions 100. The antibiotic rifamycin is selectively toxic in blocking protein synthesis in Mycobacterium tuberculosis because A. the drug binds to the initiator tRNA, preventing the formation of the protein synthesis initiation complex in the bacterial cell. B. it binds preferentially to bacterial RNA polymerase rather than the eukaryotic protein, effectively halting transcription in the pathogen but not the host. C. the antibiotic binds to the mRNA once synthesized, preventing it from participating in the initiation complex with the ribosome. D. bacterial ribosomes are 70s whereas host ribosome are 80s, thus the antibiotic binds to the M. tuberculosis ribosome but does not bind to the eukaryotic machinery.
B
10. The antiparallel arrangement within DNA molecules refers to A. each base bonding at the 1'position of the sugar. B. a purine always bonding to a pyrimidine. C. one helix strand that runs from the 5'to 3'direction and the other strand runs from the 3'to 5'direction. D. an original parent DNA strand and one newly synthesized DNA strand comprising a new DNA molecule.
C
15. Structural genes code for A. ribosomal RNA molecules. B. transfer RNA molecules. C. cellular proteins. D. gene expression elements.
C
27. A permanent, inheritable change in the genetic information is called ________. A. translation B. transcription C. a mutation D. an alteration E. regeneration
C
28. Replication of DNA begins at a/an _______ rich area. A. guanine-cytosine B. uracil-adenine C. adenine-thymine D. adenine-cytosine E. guanine-adenine
C
30. Groups of three consecutive bases along the DNA of a gene have the code for one _______. A. protein B. nucleotide C. amino acid D. purine
C
32. The RNA molecules that carry amino acids to the ribosomes during protein synthesis are called ________. A. ribosomal RNA B. messenger RNA C. transfer RNA D. primer RNA E. ribozymes
C
4. The _____ is all of the genetic material of a cell. A. proteome B. chromosome C. genome D. plasmid E. prophage
C
42. Which of the following is incorrect about termination codons? A. They are also called nonsense codons. B. They are the location where the bond between the final tRNA and the polypeptide is broken. C. They include AUG. D. They are UAA, UAG, and UGA. E. They do not have corresponding tRNA.
C
47. The operon segment composed of the gene that codes for a protein repressor is called the ________. A. operator B. structural locus C. regulator D. promoter
C
50. Full induction of the lactose operon requires A. lactose present. B. lactose and glucose present. C. lactose present without glucose. D. lactose and arabinose present.
C
51. The lactose repressor A. is transcribed with the structural lac genes. B. is activated by binding lactose. C. is inactivated by binding lactose. D. requires lactose for its transcription.
C
52. Gene regulation can involve a protein repressor that blocks ______ from initiating transcription. A. DNA polymerase I B. DNA polymerase III C. RNA polymerase D. mRNA E. rRNA
C
55. The most serious type of mutation is a ______ mutation. A. point B. silent C. frameshift D. back
C
56. If the wild type DNA sequence reads THE CAT ATE THE BIG RAT, what type of mutation would change the sequence to THE CAT ATA ETH EBI GRA T? A. Missense B. Nonsense C. Insertion D. Deletion E. Silent
C
6. A ______ is a specific segment of DNA that codes for the production of one functional product. A. intron B. exon C. gene D. operator E. triplet
C
64. Which cell can transfer the most DNA? A. F+ cell B. F-cell C. Hfr cell D. R cell E. B cell
C
65. Which of the following is not a type of bacterial DNA recombination? A. Transformation B. Conjugation C. Mitosis D. Transduction
C
68. The transfer of DNA fragments from a dead cell to a live, competent recipient cell that results in a changed recipient cell is termed ________. A. transduction B. conjugation C. transformation D. transmission E. mitosis
C
73. Which of the following additions have been made to principles of the central dogma of biology? A. DNA information cannot be converted into RNA information. B. Protein information can be converted into DNA information. C. RNA can be used to regulate gene function. D. DNA codes for proteins.
C
74. In Griffith's experiments with Streptococcus pneumoniae, rough nonencapsulated streptococci were converted into smooth encapsulated streptococci in the presence of the heat-killed smooth encapsulated streptococci. Which microbial process had Griffith identified? A. Transduction B. Conjugation C. Transformation D. Cloning
C
8. The DNA of an organism is made up of subunits called _______. A. histones B. amino acids C. nucleotides D. mRNA E. polymerases
C
96. In order for protein synthesis to begin, which of the following statements reflects the correct sequence of events? A. The AUG codon on mRNA base pairs with the UAC anticodon on tRNA allowing the small and large ribosomal subunits to join the complex. B. Translation begins when the ribosome translocates from the A site to the P site on the mRNA C. The 5'end of the mRNA binds to the small ribosomal subunit, and the large subunit joins, creating the P and A sites where reactions between codons on the mRNA and anticodons on tRNA are stabilized. D. The 3'end of the mRNA binds to the small ribosomal subunit and the AUG anticodon on the tRNA base pairs with the UAC codon on the mRNA, allowing the large ribosomal subunit to attach.
C
13. Base pairs in DNA are held together by ______ bonds. A. peptide B. nonpolar covalent C. polar covalent D. hydrogen E. sulfhydryl
D
17. Semiconservative replication refers to A. each base bonding at the 1'position of the sugar. B. a purine always bonding to a pyrimidine. C. one helix strand that runs from the 5'to 3'direction and the other strand that runs from the 3'to 5'direction. D. an original parent DNA strand and one newly synthesized DNA strand comprising a new DNA molecule.
D
20. The enzyme that helps pack DNA into the cell by coiling the DNA into a tight bundle is _______. A. DNA ligase B. DNA polymerase C. DNA helicase D. DNA gyrase E. primase
D
23. DNA gyrase A. copies DNA bases. B. synthesizes RNA primers. C. closes gaps between DNA bases. D. removes supercoiling ahead of origin.
D
29. A primer comprised of _______ is needed at the origin of nucleotide addition. A. polymerase III B. polymerase I C. helicase D. RNA E. DNA
D
38. RNA polymerase binds to the A. start codon. B. termination sequence. C. regulation sequence. D. promoter sequence.
D
40. If a codon for alanine is GCA, then the anticodon is ______. A. GCA B. CGT C. ACG D. CGU E. UGC
D
43. Which of the following is not associated with a bacterial ribosome? A. It is a 70s holoenzyme. B. It has a peptide (P) site. C. It has an exit site. D. Its small subunit provides the enzymes for making peptide bonds. E. It has an amino acid (A) site.
D
45. Split genes A. are common in bacteria and eukaryotes. B. only have exons initially transcribed to mRNA. C. have introns located only at the beginning and end of a coding region. D. are acted upon by spliceosomes to excise introns and then join exons.
D
49. Synthesis of a repressible enzyme is inhibited by A. repressor alone bound to operator. B. substrate bound to repressor. C. substrate bound to promoter. D. corepressor and repressor binding to operator.
D
5. A nucleosome is a linear chromosome wound around the _______. A. nuclear membrane B. rRNA C. mRNA D. histone E. nucleolus
D
66. Which of the following is not true of conjugation? A. Involves direct contact between cells B. Transfers genes for drug resistance C. Transfers genes for enzymes and adherence molecules D. Involves the action of bacteriophage E. The donor retains a copy of the transferred genes
D
69. The development of virulent, toxin-producing bacterial strains due to the presence of a temperate phage can occur through the process of ________. A. bacterial conjugation B. transformation C. generalized transduction D. specialized transduction
D
7. The expression of genetic traits is referred to as the organism's ______. A. genome B. genotype C. proteome D. phenotype E. proteotype
D
93. The fundamental difference between an organism's genotype and its phenotype is that A. the phenotype refers to all of the genetic material in the organism, whereas the genotype represents only the genetic material that is expressed into proteins. B. the genotype refers to the organism's genes and the phenotype refers to the non-coding segments of DNA. C. the genotype refers to eukaryotic genes that contain both introns and exons, whereas phenotype refers to bacterial DNA that has only exons. D. the genotype refers to all of the genetic material in the organism, whereas the phenotype represents only the genetic material that is expressed into proteins.
D
94. The mechanism of DNA synthesis differs between the two new daughter strands during replication. This is due to the fact that A. both RNA primers attach to the 3'end of the template strands, which are at opposite ends from each other. B. both daughter strands can't extend toward the replication fork because there would not be room for two DNA polymerase enzymes. C. one RNA primer attaches to the 5'end of the parent strand and the other primer to the 3'end. D. the DNA strands run antiparallel to each other and the DNA polymerase can only add nucleotides to the 3'end of the growing strand.
D
95. DNA polymerase can catalyze a dehydration synthesis reaction only at the 3'carbon of the daughter strand of DNA. This means that A. the antiparallel nature of the parent molecules determine that the leading strand must be grown in fragments away from the fork and the lagging strand is synthesized continuously toward the fork. B. the leading and lagging strands extend in the 3'- 5'direction toward the replication fork as the nucleotide bases are exposed. C. Okazaki fragments extend toward the replication fork as the parent strands are unzipped by helicase. D. since the strands are antiparallel, one strand will grow toward the fork as it opens, and the other strand will grow in fragments away from the fork.
D
Multiple Choice Questions 92. You have taken E. coli strain A which has its own plasmids, and mixed it with E. coli B strain without plasmids. E. coli B cells now have plasmids but, in addition, they also carry some genes from E. coli A strain. What has happened is A. the E. coli B cells have become mutants of the original culture. B. vertical transmission of DNA has occurred. C. an example of transformation. D. the cells of E. coli A were Hfr cells.
D
2. Eukaryotic chromosomes differ from bacterial chromosomes because only eukaryotes have A. histone proteins. B. chromosomes in a nucleus. C. several to many chromosomes. D. elongated, not circular, chromosomes. E. All of the choices are correct.
E
22. The site where the old DNA strands separate and new DNA strands will be synthesized is called the ________. A. primer B. Okazaki fragment C. template D. rolling circle E. replication fork
E
26. DNA Polymerase III A. synthesizes the primer. B. removes the primer. C. joins Okazaki fragments. D. unzips the DNA helix. E. proofreads new DNA.
E
3. Which of the following is not true of an organism's genotype? A. It contains structural genes that code for proteins. B. It has regulatory genes that control gene expression. C. It contains genes that code for RNA. D. It is inherited. E. It has expressed traits governed by the genes.
E
31. The three-base sequence on DNA that codes for an amino acid is called a/an ________. A. codon B. exon C. anticodon D. intron E. triplet
E
34. RNA molecules differ from DNA molecules because only RNA A. has ribose. B. has uracil. C. is typically one strand of nucleotides. D. does not have thymine. E. All of the choices are correct.
E
39. Which of the following is incorrect about transfer RNA? A. It has a bottom hairpin loop with an anticodon. B. It has an anticodon that is complementary to a codon. C. It contains a binding site for an amino acid. D. The initiator tRNA that binds to the P site has the anticodon UAC. E. The initiator tRNA in bacteria carries tryptophan.
E
44. A sequence of bases within a gene that does not code for protein is called a/n _______. A. promoter B. operator C. operon D. exon E. intron
E
54. A mutation that changes a normal codon to a stop codon is called a ______ mutation. A. point B. silent C. back D. missense E. nonsense
E
72. Which of the following is not true of transposons? A. They can change pigmentation. B. They can replace damaged DNA. C. They can transfer drug resistance. D. They can change the genome. E. They are always part of plasmids.
E
75. Of the following list, which antibiotics affect protein synthesis? A. Penicillin B. Tetracycline C. Chloramphenicol D. Ciprofloxacin E. Both tetracycline and chloramphenicol are correct.
E
Multiple Choice Questions 1. Microorganisms exhibit genomes contained on A. chromosomes. B. plasmids. C. mitochondrial DNA. D. chloroplast DNA. E. All of the choices are correct depending on the type of microorganism observed.
E
True / False Questions 99. Proteomics is the study of all proteins that are expressed by an organism, whereas genomics refers to the study of the organism's entire genome, not simply the protein-coding regions. True False
TRUE
77. DNA polymerase can only add new nucleotides to the 3'DNA end of the template. True False
True
79. Transcription occurs within the nucleus or at the nucleoid. True False
True
80. In bacteria, initiator tRNA carries formyl methionine. True False
True
82. Excised introns form structures called lariats. True False
True
84. Repressible operons are normally turned on in the cell. True False
True
86. DNA photolyase, in the presence of visible light, can repair DNA damage due to ultraviolet radiation. True False
True