AP Bio Chapters 18, 19, 20, 21
Which of the following is not a mechanism whereby a proto-oncogene is converted to an oncogene? A) methylation of bases B) point mutation C) gene transposition D) gene amplification E) chromosome translocation
A) methylation of bases
28) What are prions? A) misfolded versions of normal brain protein B) tiny molecules of RNA that infect plants C) viral DNA that has had to attach itself to the host genome D) viruses that invade bacteria E) a mobile segment of DNA
A) misfolded versions of normal brain protein
Which of the following represents an order of increasingly higher levels of organization? A) nucleosome, 30-nm chromatin fiber, looped domain B) looped domain, 30-nm chromatin fiber, nucleosome C) looped domain, nucleosome, 30-nm chromatin fiber D) nucleosome, looped domain, 30-nm chromatin fiber E) 30-nm chromatin fiber, nucleosome, looped domain
A) nucleosome, 30-nm chromatin fiber, looped domain
Under the electron microscope, unfolded chromatin resembles "beads on a string." What do the "beads" represent? A) nucleosomes B) ribosomes C) beadosomes D) molecules of DNA polymerase E) molecules of RNA polymerase
A) nucleosomes
44) What does the operon model attempt to explain? A) the coordinated control of gene expression in bacteria B) bacterial resistance to antibiotics C) how genes move between homologous regions of DNA D) the mechanism of viral attachment to a host cell E) horizontal transmission of plant viruses
A) the coordinated control of gene expression in bacteria
Bacteria that do not take up any plasmids would grow on which media? A) the nutrient broth B) the nutrient broth and the tetracycline broth C) the nutrient broth and the ampicillin broth D) the tetracycline and ampicillin broth E) all four broths
A) the nutrient broth
A eukaryotic protein can be made in bacteria by inserting the gene encoding the protein into a(n) A) protein plasmid. B) expression vector. C) yeast artificial chromosome (YAC). D) PCR vector. E) restriction plasmid.
B) expression vector
22) If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities? A) I B) II C) III D) IV E) either II or IV
C
In a nucleosome, what is the DNA wrapped around? A) polymerase molecules B) ribosomes C) mRNA D) histones E) nucleolus protein
D) histones
What is the enzymatic function of restriction enzymes? A) to add new nucleotides to the growing strand of DNA B) to join nucleotides during replication C) to join nucleotides during transcription D) to cleave nucleic acids at specific sites E) to repair breaks in sugar-phosphate backbones
D) to cleave nucleic acids at specific sites
A. transduction B. transposition C. translation D. transformation E. conjugation 32) External DNA is assimilated by a cell.
D) transformation
The condensed chromosomes observed in mitosis include all of the following structures except A) nucleosomes. B) 30-nm fibers. C) 300-nm fibers. D) looped domain. E) ribosomes.
E) ribosomes
Which of the following is not a characteristic of the product of the p53 gene? It A) is an activator for other genes. B) slows down the cell cycle. C) causes cell death. D) prevents cells from passing on mutations due to DNA damage. E) slows down the rate of DNA replication by interfering with the binding of DNA polymerase.
E) slows down the rate of DNA replication by interfering with the binding of DNA polymerase.
The questions below refer to the following terms. Each term may be used once, more than once, or not at all. A. enhancer B. promoter C. activator D. repressor E. terminator site in the DNA located near the end of the final exon, encoding an RNA sequence that determines the 3' end of the transcript
E) terminator
10) Which of the following statements about the lysogenic cycle of lambda (λ) phage is incorrect? A) After infection the viral genes immediately turn the host cell into a lambda-producing factory, and the host cell then lyses. B) Most of the prophage genes are silenced by the product of a particular prophage gene. C) The phage genome replicates along with the host genome. D) Certain environmental triggers can cause the phage to exit the host genome, switching from the lysogenic to the lytic cycle. E) The phage DNA is incorporated by genetic recombination (crossing over) into a specific site on the host cell's DNA.
A) After infection the viral genes immediately turn the host cell into a lambda-producing factory, and the host cell then lyses.
Why do histones bind tightly to DNA? A) Histones are positively charged, and DNA is negatively charged. B) Histones are negatively charged, and DNA is positively charged. C) Both histones and DNA are strongly hydrophobic. D) Histones are covalently linked to the DNA. E) Histones are highly hydrophobic, and DNA is hydrophilic.
A) Histones are positively charged, and DNA is negatively charged.
You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent. I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope III. culturing the substance by itself on nutritive medium, away from any plant cells IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious 21) Which treatment could definitively determine whether or not the component is a viroid? A) I B) II C) III D) IV E) first II and then III
A) I
The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called A) RNA interference. B) RNA obstruction. C) RNA blocking. D) RNA targeting. E) RNA disposal.
A) RNA interference
54) Which of the following statements about operons is (are) true? A) The tryptophan operon is a repressible operon. B) Tryptophan itself can bind to the trp operator and shut down production of tryptophan pathway enzymes. C) The lactose operon repressor binds to the operator and turns on the synthesis of the enzyme β-galactosidase. D) Only A and C are correct. E) A, B, and C are correct.
A) The tryptophan operon is a repressible operon.
42) Which of the following statements regarding transposons is not true? A) Transposons are genes that encode sex pili and enable plasmid transfers between bacteria. B) Transposons are found in both prokaryotes and eukaryotes. C) Transposons can move from a plasmid to the bacterial circular chromosome. D) Transposons may replicate at an original site and insert a copy at another site. E) Transposons may carry only the genes necessary for insertion.
A) Transposons are genes that encode sex pili and enable plasmid transfers between bacteria.
1) Which of the following is (are) true about viruses? A) Viruses are classified below the cellular level of biological organization. B) A single virus particle contains both DNA and RNA. C) Even small virus particles are visible with light microscopes. D) Only A and B are true. E) A, B, and C are true.
A) Viruses are classified below the cellular level of biological organization.
Plasmids are important in biotechnology because they are A) a vehicle for the insertion of foreign genes into bacteria. B) recognition sites on recombinant DNA strands. C) surfaces for protein synthesis in eukaryotic recombinants. D) surfaces for respiratory processes in bacteria. E) proviruses incorporated into the host DNA.
A) a vehicle for the insertion of foreign genes into bacteria.
How does a bacterial cell protect its own DNA from restriction enzymes? A) by adding methyl groups to adenines and cytosines B) using DNA ligase to seal the bacterial DNA into a closed circle C) adding histones to protect the double-stranded DNA D) by forming "sticky ends" of bacterial DNA to prevent the enzyme from attaching E) by reinforcing the bacterial DNA structure with covalent phosphodiester bonds
A) by adding methyl groups to adenines and cytosines
51) A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in A) continuous transcription of the structural gene controlled by that regulator. B) complete inhibition of transcription of the structural gene controlled by that regulator. C) irreversible binding of the repressor to the operator. D) inactivation of RNA polymerase. E) both B and C
A) continuous transcription of the structural gene controlled by that regulator.
43) An R plasmid can A) facilitate bacterial resistance to antibiotics. B) adjust the rates of metabolic pathways. C) repress gene expression. D) convert an F+ to an F- bacterium. E) reverse the direction of transcription.
A) facilitate bacterial resistance to antibiotics.
16) Viral envelopes contain proteins with covalently attached carbohydrate groups called A) glycoproteins. B) proteosugars. C) carbopeptides. D) peptidocarbs. E) carboproteins.
A) glycoproteins.
The DNA fragments making up a genomic library are generally contained in A) recombinant plasmids of bacteria. B) recombinant viral DNA. C) eukaryotic chromosomes. D) both A and B E) A, B, and C
A) recombinant plasmids of bacteria.
45) All of the following are made up of nucleic acid except a A) repressor. B) structural gene. C) promoter. D) regulatory gene. E) operator.
A) repressor.
13) Viruses with single-stranded RNA that acts as a template for DNA synthesis are known as A) retroviruses. B) proviruses. C) viroids. D) bacteriophages. E) lytic phages.
A) retroviruses.
7) Viruses are referred to as obligate parasites because A) they cannot reproduce outside of a host cell. B) viral DNA always inserts itself into host DNA. C) they invariably kill any cell they infect. D) they can incorporate nucleic acids from other viruses. E) they must use enzymes encoded by the virus itself.
A) they cannot reproduce outside of a host cell.
In both eukaryotes and prokaryotes, gene expression is primarily regulated at the level of A) transcription. B) translation. C) mRNA stability. D) mRNA splicing. E) protein stability.
A) transcription
A. transduction B. transposition C. translation D. transformation E. conjugation 33) DNA is transferred from one bacterium to another by a virus
A) transduction
37) In biotechnology, genes are commonly introduced into bacterial cells by incubating the cells together with DNA and high concentrations of calcium ions. This is an example of A) transformation. B) translocation. C) transduction. D) conjugation. E) transposition.
A) transformation
A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. A likely explanation for the lack of transgene expression in the fifth cell line is that the A) transgene integrated into a heterochromatic region of the genome. B) transgene integrated into a euchromatic region of the genome. C) transgene was mutated during the process of integration into the host cell genome. D) host cell lacks the enzymes necessary to express the transgene. E) transgene integrated into a region of the genome characterized by high histone acetylation.
A) transgene integrated into a heterochromatic region of the genome.
27) The difference between vertical and horizontal transmission of plant viruses is that A) vertical transmission refers to the transmission of a virus from a parent plant to its progeny, and horizontal transmission refers to one plant spreading the virus to another plant. B) vertical transmission refers to the spread of viruses from upper leaves to lower leaves of the plant, and horizontal transmission refers to the spread of a virus among leaves at the same general level. C) vertical transmission refers to the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission refers to the spread of viruses among plants of similar size. D) vertical transmission refers to the transfer of DNA from one type of plant virus to another, and horizontal transmission refers to the exchange of DNA between two plant viruses of the same type. E) vertical transmission refers to the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission refers to the spread of viruses among plants of the same species.
A) vertical transmission refers to the transmission of a virus from a parent plant to its progeny, and horizontal transmission refers to one plant spreading the virus to another plant.
Scientists developed a set of guidelines to address the safety of DNA technology. Which of the following is one of the adopted safety measures? A. Microorganisms used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside of the laboratory. B. Genetically modified organisms cannot be part of our food supply. C. Transgenic plants are engineered so that the plant genes cannot hybridize. D. Experiments involving HIV or other potentially dangerous viruses have been banned. E. Recombinant plasmids cannot be replicated.
A. Microorganisms used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside of the laboratory.
57) Allolactose induces the synthesis of the enzyme lactase. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell? A) The repressor protein attaches to the regulator. B) Allolactose binds to the repressor protein. C) Allolactose binds to the regulator. D) The repressor protein and allolactose bind to RNA polymerase. E) RNA polymerase attaches to the regulator.
B) Allolactose binds to the repressor protein.
14) What is the function of reverse transcriptase in retroviruses? A) It hydrolyzes the host cell's DNA. B) It uses viral RNA as a template for DNA synthesis. C) It converts host cell RNA into viral DNA. D) It translates viral RNA into proteins. E) It uses viral RNA as a template for making complementary RNA strands.
B) It uses viral RNA as a template for DNA synthesis.
If a cell were unable to produce histone proteins, which of the following would be expected to occur? A) There would be an increase in the amount of "satellite" DNA produced during centrifugation. B) The cell's DNA couldn't be packed into its nucleus. C) Spindle fibers would not form during prophase. D) Amplification of other genes would compensate for the lack of histones. E) Pseudogenes would be transcribed to compensate for the decreased protein in the cell.
B) The cell's DNA couldn't be packed into its nucleus.
25) Which of the following is true of plant virus infections? A) They can be controlled by the use of antibiotics. B) They are spread throughout a plant by passing through the plasmodesmata. C) They have little effect on plant growth. D) Only A and B are correct. E) A, B, and C are correct.
B) They are spread throughout a plant by passing through the plasmodesmata.
18) Which of the following is a true statement? A) Viruses are uncommon. B) Viruses can cause diarrhea, colds, and measles. C) All viruses have a similar capsid and membranous envelope. D) All viruses contain the nucleic acid RNA. E) Viruses only invade animal cells.
B) Viruses can cause diarrhea, colds, and measles.
26) Which of the following represents a difference between viruses and viroids? A) Viruses infect many types of cells, whereas viroids infect only prokaryotic cells. B) Viruses have capsids composed of protein, whereas viroids have no capsids. C) Viruses contain introns; viroids have only exons. D) Viruses always have genomes composed of DNA, whereas viroids always have genomes composed of RNA. E) Viruses cannot pass through plasmodesmata; viroids can.
B) Viruses have capsids composed of protein, whereas viroids have no capsids.
40) What does bacterial mating involve? A) exchange of egg and sperm B) formation of a cytoplasmic bridge for the transfer of "male" DNA C) sex pili that draw the cells together so that mRNA can be inserted D) integration of male and female DNA into a cytoplasmic bridge E) binary fission of a bacterial cell
B) formation of a cytoplasmic bridge for the transfer of "male" DNA
A. transduction B. transposition C. translation D. transformation E. conjugation 36) A sequence of DNA is moved to alternative locations within the genome.
B) transposition
Which of the following is least related to the others? A) 30-nm chromatin fiber B) pseudogenes C) nucleosomes D) looped domains E) histones
B) pseudogenes
20) RNA viruses appear to have higher rates of mutation because A) RNA nucleotides are more unstable than DNA nucleotides. B) replication of their genomes does not involve the proofreading steps of DNA replication. C) RNA viruses replicate faster. D) RNA viruses can incorporate a variety of nonstandard bases. E) RNA viruses are more sensitive to mutagens
B) replication of their genomes does not involve the proofreading steps of DNA replication.
53) Transcription of the structural genes in an inducible operon A) occurs all the time. B) starts when the pathway's substrate is present. C) starts when the pathway's product is present. D) stops when the pathway's product is present. E) does not produce enzymes.
B) starts when the pathway's substrate is present.
Genetically engineered plants A. are more difficult to engineer than animals. B. include a transgenic rice plant that could help prevent vitamin A deficiency. C. are being rapidly developed, but traditional plant breeding programs are still the only method used to develop new plants. D. are able to fix nitrogen themselves. E. are banned throughout the world.
B. include a transgenic rice plant that could help prevent vitamin A deficiency.
Which enzyme was used to produce the molecule in the figure below? A) ligase B) transcriptase C) a restriction enzyme D) RNA polymerase E) DNA polymerase
C) a restriction enzyme
How does a genomic library differ from a cDNA library? A) A genomic library contains both noncoding sequences and coding sequences, whereas a cDNA library contains only coding sequences. B) A genomic library is identical regardless of the cell type used to make it, whereas the content of a cDNA library depends on the cell type used in its construction. C) A genomic library can be made using a restriction enzyme and DNA ligase only, whereas a cDNA library requires both of these as well as reverse transcriptase and DNA polymerase. D) Only B and C are correct. E) A, B and C are correct.
C) A genomic library can be made using a restriction enzyme and DNA ligase only, whereas a cDNA library requires both of these as well as reverse transcriptase and DNA polymerase.
Which of the following statements is true? A) Heterochromatin is composed of DNA, whereas euchromatin is made of DNA and RNA. B) Both heterochromatin and euchromatin are found in the cytoplasm. C) Heterochromatin is highly condensed, whereas euchromatin is less compact. D) Euchromatin is not transcribed, whereas heterochromatin is transcribed. E) Only euchromatin is visible under the light microscope.
C) Heterochromatin is highly condensed, whereas euchromatin is less compact.
What are the typical characteristics of a cloning vector? A) Bacterial cells cannot survive without it when grown under certain conditions. B) It contains restriction sites that allow the insertion of foreign DNA segments. C) It can replicate in bacterial cells. D) Only B and C are correct. E) A, B, and C are correct.
C) It can replicate in bacterial cells.
56) For a repressible operon to be transcribed, which of the following must be true? A) A corepressor must be present. B) RNA polymerase and the active repressor must be present. C) RNA polymerase must bind to the promoter, and the repressor must be inactive. D) RNA polymerase cannot be present, and the repressor must be inactive. E) RNA polymerase must not occupy the promoter, and the repressor must be inactive
C) RNA polymerase must bind to the promoter, and the repressor must be inactive.
If you discovered a bacterial cell that contained no restriction enzymes, which of the following would you expect to happen? A) The cell would be unable to replicate its DNA. B) The cell would create incomplete plasmids. C) The cell would be easily infected and lysed by bacteriophages. D) The cell would become an obligate parasite. E) Both A and D would occur.
C) The cell would be easily infected and lysed by bacteriophages.
Which of the following statements concerning the eukaryotic chromosome is false? A) It is composed of DNA and protein. B) The nucleosome is the most basic structural subunit. C) The number of genes on each chromosome is different in different cell types. D) It consists of a single linear molecule of double-stranded DNA. E) Active transcription occurs on euchromatin.
C) The number of genes on each chromosome is different in different cell types.
3) A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur? A) The plants would develop some but not all of the symptoms of the TMV infection. B) The plants would develop symptoms typically produced by viroids. C) The plants would develop the typical symptoms of TMV infection. D) The plants would not show any disease symptoms. E) The plants would become infected, but the sap from these plants would be unable to infect other plants.
C) The plants would develop the typical symptoms of TMV infection. D) The plants would not show any disease symptoms.
39) A scientist is studying a strain of bacteria that commonly transfers genes to other bacteria. Which of the following would provide evidence that the genes are being transferred through specialized transduction? A) Transmission of the genes is always accompanied by transfer of the F plasmid. B) Transmission of the genes is always accompanied by transfer of the R plasmid. C) The same one or several gene(s) are always transferred. D) The transmission of the genes is dramatically enhanced in the presence of calcium. E) The bacterial strain is often infected by a virulent phage.
C) The same one or several gene(s) are always transferred
Which of the following statements concerning proto-oncogenes is false? A) They can code for proteins associated with cell growth. B) They are similar to oncogenes found in retroviruses. C) They are produced by somatic mutations induced by carcinogenic substances. D) They can be involved in producing proteins for cell adhesion. E) They can code for proteins involved in cell division.
C) They are produced by somatic mutations induced by carcinogenic substances.
The questions below refer to the following terms. Each term may be used once, more than once, or not at all. A. enhancer B. promoter C. activator D. repressor E. terminator binds to a site in the DNA far from the promoter to stimulate transcription
C) activator
What is a cloning vector? A) an enzyme that cuts DNA into restriction fragments B) a DNA probe used to locate a particular gene in the genome C) an agent, such as a plasmid, used to transfer DNA from an in vitro solution into a living cell D) the laboratory apparatus used to clone genes E) the sticky end of a DNA fragment
C) an agent, such as a plasmid, used to transfer DNA from an in vitro solution into a living cell
A eukaryotic gene typically has all of the following features except A) introns. B) a promoter. C) an operator. D) control elements. E) a terminator.
C) an operator
The principal problem with inserting an unmodified mammalian gene into a bacterial plasmid, and then getting that gene expressed in bacteria, is that A) prokaryotes use a different genetic code from that of eukaryotes. B) bacteria translate polycistronic messages only. C) bacteria cannot remove eukaryotic introns. D) bacterial RNA polymerase cannot make RNA complementary to mammalian DNA. E) bacterial DNA is not found in a membrane-bounded nucleus and is therefore incompatible with mammalian DNA.
C) bacteria cannot remove eukaryotic introns.
Tumor suppressor genes A) are frequently overexpressed in cancerous cells. B) are cancer-causing genes introduced into cells by viruses. C) can encode proteins that promote DNA repair or cell-cell adhesion. D) often encode proteins that stimulate the cell cycle. E) all of the above
C) can encode proteins that promote DNA repair or cell-cell adhesion.
Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to A) insert the fragments cut with X directly into the plasmid without cutting the plasmid. B) cut the plasmid with restriction enzyme X and insert the fragments cut with Y into the plasmid. C) cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme. D) cut the plasmid twice with restriction enzyme Y and ligate the two fragments onto the ends of the DNA fragments cut with restriction enzyme X. E) cut the plasmid with enzyme X and then insert the gene into the plasmid.
C) cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.
Bacteria containing recombinant plasmids are often identified by which process? A) examining the cells with an electron microscope B) using radioactive tracers to locate the plasmids C) exposing the bacteria to an antibiotic that kills cells lacking the plasmid D) removing the DNA of all cells in a culture to see which cells have plasmids E) producing antibodies specific for each bacterium containing a recombinant plasmid
C) exposing the bacteria to an antibiotic that kills cells lacking the plasmid
If you were to observe the activity of methylated DNA, you would expect it to A) be replicating. 3 B) be unwinding in preparation for protein synthesis. C) have turned off or slowed down the process of transcription. D) be very active in translation. E) induce protein synthesis by not allowing repressors to bind to it.
C) have turned off or slowed down the process of transcription
In a nucleosome, the DNA is wrapped around A) polymerase molecules. B) ribosomes. C) histones. D) the nucleolus. E) satellite DNA.
C) histones.
In which of the following would you expect to find the most methylation of DNA? A) tandem arrays for ribosomal genes B) pseudogenes C) inactivated mammalian X chromosomes D) globin genes E) transposons
C) inactivated mammalian X chromosomes
11) Virulent phages undergo a(n) ________ life cycle, whereas temperate phages are capable of undergoing a(n) ________ cycle. A) infective; retroviral B) lysogenic; lytic C) lytic; lysogenic D) retroviral; infective E) infective; benign
C) lytic; lysogenic
During DNA replication, A) all methylation of the DNA is lost. B) DNA polymerase is blocked by methyl groups, and methylated regions of the genome are therefore left uncopied. C) methylation of the DNA is maintained because methylation enzymes act at DNA sites where one strand is already methylated and thus correctly methylates daughter strands after replication. D) methylation of the DNA is maintained because DNA polymerase directly incorporates methylated nucleotides into the new strand opposite any methylated nucleotides in the template. E) methylated DNA is copied in the cytoplasm, and unmethylated DNA in the nucleus.
C) methylation of the DNA is maintained because methylation enzymes act at DNA sites where one strand is already methylated and thus correctly methylates daughter strands after replication
A significant difference between eukaryotes and prokaryotes is that A) DNA is wound around proteins to form chromatin in eukaryotes, but in prokaryotes the DNA is not associated with proteins. B) gene expression is largely regulated by transcription in prokaryotes, but not in eukaryotes. C) prokaryotic genes do not contain introns. D) noncoding DNA sequences are found in prokaryotes, but not in eukaryotes. E) prokaryotes have less DNA but more noncoding segments than eukaryotes.
C) prokaryotic genes do not contain introns
A. operon B. inducer C. promoter D. repressor E. corepressor 49) A mutation in this section of DNA could influence the binding of RNA polymerase to the DNA.
C) promoter
9) Bacteriophage DNA that have become integrated into the host cell chromosome are called A) intemperate bacteriophages. B) transposons. C) prophages. D) T-even phages. E) plasmids.
C) prophages.
A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using A) RNA polymerase to transcribe the gene. B) a restriction enzyme to cut the gene into shorter pieces. C) reverse transcriptase to reconstruct the gene from its mRNA. D) DNA polymerase to reconstruct the gene from its polypeptide product. E) DNA ligase to put together fragments of the DNA that codes for a particular polypeptide.
C) reverse transcriptase to reconstruct the gene from its mRNA.
Which of the following is least related to the others? A) cyclins B) ubiquitin C) tumor suppression D) protein degradation E) proteasomes
C) tumor suppression
17) The simplest infectious biological systems are A) bacteria. B) viruses. C) viroids. D) both A and B E) both B and C
C) viroids.
19) Which of the following can be effective against viral diseases? A) vaccination B) nucleoside analogs that inhibit DNA synthesis C) antibiotics D) A and B only E) A, B, and C
D) A and B only
24) Which of the following contributes to the emergence of viral disease? A) production of new virus strains through mutation B) spread of existing virus from one host species to another C) transformation from lytic to lysogenic activity D) A and B only E) A, B, and C
D) A and B only
4) Which of the following is a characteristic of all viruses? A) a nucleic acid genome B) a protein capsid C) a viral envelope D) A and B only E) A, B, and C
D) A and B only
Which of the following mechanisms is (are) used to coordinately control the expression of multiple, related genes in eukaryotic cells? A) organization of the genes into clusters, with local chromatin structures influencing the expression of all the genes at once B) each of the genes sharing a common control element, allowing a single activator to turn on their transcription at once, regardless of their location in the genome C) organizing the genes into large operons, allowing them to be transcribed as a single unit D) A and B only E) A, B , and C
D) A and B only
8) Which of the following is characteristic of the lytic cycle? A) Many bacterial cells containing viral DNA are produced. B) Viral DNA is incorporated into the host genome. C) The viral genome replicates without destroying the host. D) A large number of phages are released at a time. E) The virus-host relationship usually lasts for generations.
D) A large number of phages are released at a time.
Which of the following statements about histones is incorrect? A) Each nucleosome consists of two molecules, each of four types of histone. B) Histone H1 is not present in the nucleosome bead; instead it is involved in the formation of higher-level chromatin structures. C) The amino end of each histone extends outward from the nucleosome and is called a "histone tail." D) Histones are found in mammals, but not in other animals or in plants. E) The mass of histone in chromatin is approximately equal to the mass of DNA.
D) Histones are found in mammals, but not in other animals or in plants.
What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? I. Transform bacteria with recombinant DNA molecule. II. Cut the plasmid DNA using restriction enzymes. III. Extract plasmid DNA from bacterial cells. IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. V. Use ligase to seal plasmid DNA to nonplasmid DNA. A) I, II, IV, III, V B) II, III, V, IV, I C) III, II, IV, V, I D) III, IV, V, I, II E) IV, V, I, II, III
D) III, IV, V, I, II
23) Which treatment would you use to determine if the agent is a prion? A) I only B) II only C) III only D) IV only E) either I or IV
D) IV only
55) How does active CAP induce expression of the genes of the lactose operon? A) It terminates production of repressor molecules. B) It degrades the substrate allolactose. C) It stimulates splicing of the encoded genes. D) It stimulates the binding of RNA polymerase to the promoter. E) It binds steroid hormones and controls translation
D) It stimulates the binding of RNA polymerase to the promoter.
2) Which of the following is not a reason scientists suspected that something other than bacteria was the cause of tobacco mosaic disease? A) Passing infectious sap through a fine filter failed to remove the infectious agent. B) Treating infectious sap with alcohol failed to remove the infectious agent. C) No cells could be seen in the infectious sap using a light microscope. D) The infectious agent in the sap could reproduce, as its ability to cause disease was undiluted even after many transfers from plant to plant. E) The infectious agent could not be cultivated on nutrient media in petri dishes or in test tubes.
D) The infectious agent in the sap could reproduce, as its ability to cause disease was undiluted even after many transfers from plant to plant.
Steroid hormones produce their effects in cells by A) activating key enzymes in metabolic pathways. B) activating translation of certain mRNAs. C) promoting the degradation of specific mRNAs. D) binding to intracellular receptors and promoting transcription of specific genes. E) promoting the formation of looped domains in certain regions of DNA.
D) binding to intracellular receptors and promoting
Yeast cells are frequently used as hosts for cloning because A) they are easy to grow. B) they can remove introns from mRNA. C) they have plasmids. D) both A and B E) A, B, and C
D) both A and B
A. operon B. inducer C. promoter D. repressor E. corepressor 48) This protein is produced by a regulatory gene.
D) repressor
Muscle cells and nerve cells in one species of animal owe their differences in structure to A) having different genes. B) having different chromosomes. C) using different genetic codes. D) differential gene expression. E) having unique ribosomes.
D) differential gene expression.
Genomic imprinting, DNA methylation, and histone acetylation are all examples of A) genetic mutation. B) chromosomal rearrangements. C) karyotypes. D) epigenetic inheritance. E) translocation.
D) epigenetic inheritance
38) The process by which host cell DNA is accidentally packaged within a phage capsid and transferred to another cell instead of the phage DNA is called A) translocation. B) conjugation. C) specialized transduction. D) generalized transduction. E) transformation.
D) generalized transduction
A eukaryotic gene has "sticky ends" produced by the restriction endonuclease EcoRI. The gene is added to a mixture containing EcoRI and a bacterial plasmid that carries two genes conferring resistance to ampicillin and tetracycline. The plasmid has one recognition site for EcoRI located in the tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are streaked on a plate using a technique that produces isolated colonies that are clones of the original. Samples of these colonies are then grown in four different media: nutrient broth plus ampicillin, nutrient broth plus tetracycline, nutrient broth plus ampicillin and tetracycline, and nutrient broth without antibiotics. Bacteria that contain the plasmid, but without the eukaryotic gene, would grow A) in the nutrient broth plus ampicillin, but not in the broth containing tetracycline. B) only in the broth containing both antibiotics. C) in the broth containing tetracycline, but not in the broth containing ampicillin. D) in all four types of broth. E) in the nutrient broth without antibiotics only.
D) in all four types of broth
The polymerase chain reaction is important because it allows us to A) insert eukaryotic genes into prokaryotic plasmids. B) incorporate genes into viruses. C) make DNA from RNA transcripts. D) make many copies of a targeted segment of DNA. E) insert regulatory sequences into eukaryotic genes.
D) make many copies of a targeted segment of DNA.
Two potential devices that eukaryotic cells use to regulate transcription are DNA ________ and histone ________. A) methylation; amplification B) amplification; methylation C) acetylation; methylation D) methylation; acetylation E) amplification; acetylation
D) methylation; acetylation
The questions below refer to the following terms. Each term may be used once, more than once, or not at all. A. enhancer B. promoter C. activator D. repressor E. terminator can inhibit transcription by blocking the binding of positively acting transcription factors to the DNA
D) repressor
30) Reproduction in bacteria requires A) the production of a mitotic spindle. B) a plasmid. C) cyclic AMP. D) replication of DNA. E) both B and D
D) replication of DNA.
58) Of the following, which is least related to the others? A) corepressor B) repressor C) inducer D) transposon E) cAMP receptor protein
D) transposon
What is the enzymatic function of restriction enzymes? A. to add new nucleotides to the growing strand of DNA B. to join nucleotides during replication C. to join nucleotides during transcription D. to cleave nucleic acids at specific sites E. to repair breaks in sugar-phosphate backbones
D. to cleave nucleic acids at specific sites
Approximately what proportion of the DNA in the human genome codes for proteins or functional RNA? A) 83% B) 46% C) 32% D) 13% E) 2%
E) 2%
Eukaryotic cells control gene expression by which of the following mechanisms? A) histone acetylation of nucleosomes B) DNA methylation C) enzyme modification of chromatin structure D) A and B only E) A, B, and C
E) A, B, and C
12) What is the function of the single-stranded RNA in certain animal viruses? A) It can serve directly as mRNA. B) It can serve as a template for mRNA synthesis. C) It can serve as a template for DNA synthesis. D) Only A and C are correct. E) A, B, and C are correct.
E) A, B, and C are correct.
A. operon B. inducer C. promoter D. repressor E. corepressor 50) A lack of this nonprotein molecule would result in the inability of the cell to "turn off" genes.
E) corepressor
29) Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory? A) Viruses contain either DNA or RNA. B) Viruses are enclosed in protein capsids rather than plasma membranes. C) Viruses can reproduce only inside host cells. D) Viruses can infect both prokaryotic and eukaryotic cells. E) Viral genomes are usually more similar to the genome of the host cell than to the genomes of viruses that infect other cell types.
E) Viral genomes are usually more similar to the genome of the host cell than to the genomes of viruses that infect other cell types.
41) An Hfr bacterium is one that has A) at least one plasmid present in the cytosol. B) a special recognition site that will take up closely related DNA from its environment. C) several insertion sequences scattered throughout its chromosome. D) several copies of a single transposon repeated randomly throughout its chromosome. E) a plasmid that has become integrated into its chromosome.
E) a plasmid that has become integrated into its chromosome.
General transcription factors A) are required for the expression of all protein-encoding genes. B) bind to other proteins or to a sequence element within the promoter called the TATA box. C) help RNA polymerase bind to the promoter and begin transcribing. D) usually only lead to a low level of transcription in the absence of additional proteins called specific transcription factors. E) all of the above
E) all of the above
The completion of the Human Genome Project revealed that the human genome contains fewer genes than expected, not so many more than simpler organisms. How can this be reconciled with the greater complexity of humans relative to many other organisms? A. RNA transcripts of human genes are more likely to undergo alternative splicing. B. Post-translational processing adds diversity to the resulting polypeptides. C. Polypeptide domains are combined in a variety of ways. D. Gene expression patterns in humans are often more complex than those in other organisms. E. All of the above are correct.
E) all of the above are correct
46) The role of a metabolite that controls a repressible operon is to A) bind to the promoter region and decrease the affinity of RNA polymerase for the promoter. B) bind to the operator region and block the attachment of RNA polymerase to the promoter. C) increase the production of inactive repressor proteins. D) bind to the repressor protein and inactivate it. E) bind to the repressor protein and activate it.
E) bind to the repressor protein and activate it.
37) Which of the following events is (are) necessary for the production of a malignant tumor? A) activation of an oncogene in the cell B) inactivation of tumor-suppressor genes within the cell C) presence of mutagenic substances within the cell's environment D) presence of a retrovirus within the cell E) both A and B
E) both A and B
6) The host range of a virus is determined by A) the proteins on its surface. B) whether its nucleic acid is DNA or RNA. C) the proteins on the surface of the host cell. D) the enzymes produced by the virus before it infects the cell. E) both A and C
E) both A and C
15) The membrane making up the viral envelope can come from A) the virus itself, using enzymes encoded by the virus. B) the nuclear membrane of an infected cell. C) the plasma membrane of an infected cell. D) both A and B E) both B and C
E) both B and C
52) The lactose operon is likely to be transcribed when A) there is more glucose in the cell than lactose. B) the cyclic AMP levels are low. C) there is lactose but no glucose in the cell. D) the cyclic AMP and lactose levels are both high within the cell. E) both C and D
E) both C and D
In eukaryotes, transcription is generally associated with A) euchromatin only. B) heterochromatin only. C) very tightly packed DNA only. D) highly methylated DNA only. E) both euchromatin and histone acetylation.
E) both euchromatin and histone acetylation
A. transduction B. transposition C. translation D. transformation E. conjugation 34) A group of F+ bacteria is mixed with a group of F- bacteria. After several days, all of the bacteria are F+.
E) conjugation
A. transduction B. transposition C. translation D. transformation E. conjugation 35) A plasmid is exchanged between bacteria through a pilus.
E) conjugation
5) Viral genomes can consist of any of the following except A) double-stranded DNA. B) double-stranded RNA. C) single-stranded DNA. D) single-stranded RNA. E) helical capsomeres.
E) helical capsomeres.
31) What is the most common source of genetic diversity in a bacterial colony? A) transposons B) plasmids C) meiotic recombination D) crossing over E) mutation
E) mutation
Bacteria containing a plasmid into which the eukaryotic gene has integrated would grow in A) the nutrient broth only. B) the nutrient broth and the tetracycline broth only. C) the nutrient broth, the ampicillin broth, and the tetracycline broth. D) all four types of broth. E) the ampicillin broth and the nutrient broth.
E) the ampicillin broth and the nutrient broth.
47) The tryptophan operon is a repressible operon that is A) permanently turned on. B) turned on only when tryptophan is present in the growth medium. C) turned off only when glucose is present in the growth medium. D) turned on only when glucose is present in the growth medium. E) turned off whenever tryptophan is added to the growth medium.
E) turned off whenever tryptophan is added to the growth medium.
