Deck 17: Recombinant DNA Technology

Question 1

Which cloning vector should be used to express a 500-kb DNA fragment in Saccharomyces cerevisiae?

A)YAC
B)BAC
C)pUC19
D) $\lambda$ 1059

Answer 1

YAC

Question 2

Which is most analogous to the role of GFP in recombinant DNA technology?

A)Using dyes to stain and detect bacteria under light microscopy from the sputum of a patient diagnosed with tuberculosis.
B)Comparing the RFLP patterns of DNA from various suspects to DNA isolated from the scene of a crime using gel electrophoresis.
C)Creating a metagenomic library representing archaea bacteria that thrive in the hot springs of Yellowstone National Park.
D)Monitoring the spread of multi-drug resistant pathogens on a hospital floor by comparing antibiotic susceptibility patterns.

Answer 2

A

Question 3

Which of the following components of PCR ensures amplification of the target DNA sequence only,despite the presence of many other DNA sequences?

A)Primers
B)Polymerases
C)dNTPs
D)High temperatures

Answer 3

A

Question 4

Some plasmid vectors have incorporated the regulatory sequences of the lactose operon so that the expression of the recombinant gene can be induced at the appropriate time.

Question 5

A microbial ecologist who is interested in studying how gene expression is influenced by different species of bacteria in a biofilm would most likely find a metagenomic library more useful than a genomic library.

Question 6

Regardless of the exact approach taken to recombinant DNA technology,one of the keys to successful cloning is choosing the right vector.

Question 7

As a newly hired molecular biologist for a company that produces genetically modified seeds,your first project is to ensure that a GM cotton plant carrying a bacterial insecticide gene is expressed in tissues of seedlings as well as mature plants.To better understand regulation of the gene,you decide to use GFP fusion to detect activity of the promoter and also use GFP fusion to determine the location of the protein in plants tissues at various stages of growth.

A)transcriptional; translational
B)translational; transcriptional
C)transcriptional; transcriptional
D)translational; translational

Question 8

You and a friend are student assistants in a research laboratory that investigates the anti-cancer properties of proteins isolated from marine organisms.Your friend mentions that she is using a BAC vector to insert shark DNA into Escherichia coli,but after repeated attempts,has found that the bacterial cells fail to synthesize the encoded protein.What is your advice?

A)If the shark DNA is unmodified,it contains introns that are not recognized by bacteria,therefore protein synthesis will not occur.
B)Since shark DNA is eukaryotic,the cloning vector should be a YAC derived from yeast rather than a BAC derived from bacteria.
C)It is impossible to clone eukaryotic DNA into a bacterial host,since eukaryotic DNA has introns and prokaryotic DNA does not.
D)Because Escherichia coli is not naturally competent,it cannot serve as the cloning host for foreign DNA.

Question 9

A molecular biologist is interested in purify a recombinant protein by His-tagging,but the protein and vector both lack histidine residues.In this case,the molecular biologist could use which of the following technique(s)to acheive purification?

A)Add a 6xHis-tag to the C-terminus of the protein.
B)Add a series of histidine residues to the N-terminus of the protein.
C)Amplify the histidine-encoding sequence by PCR and add it to the gene of interest.
D)All of the choices are correct.

Question 10

A (n)__________ vector contains promoters that result in high-level transcription of the gene cloned within a multicloning site.

A)shuttle
B)chimeric
C)expression
D)phage

Question 11

Which of the following terms is most closely related to genetic complementation?

A)Phenotypic rescue
B)Naked DNA
C)Reverse transcription
D)SOS response

Question 12

When a eukaryotic gene is expressed in a bacterium,the eukaryotic regulatory sequences should be maintained in order to achieve maximum expression of the gene.

Question 13

Which of the following bacterial hosts would should be used to avoid degradation of DNA that is introduced via a cloning vector?

A)Escherichia coli that lack endonucleases
B)RecA-expressing Escherchia coli
C)Escherchia coli RecA mutants
D)Saccharomyces cerevisiae wild type cells

Question 14

During the investigation of a convenience store robbery,witnesses report that the perpetrator exited through a main entry door without wearing gloves.The police are holding a prime suspect in custody while samples from the door are collected and analyzed for a DNA match.Since the door was handled by many people before the robbery,how will the forensics department distinguish the suspect's DNA from the DNA of others using PCR?

A)Sequence-specific primers to the suspect's DNA will be used for PCR amplification.
B)Sequence-specific primers to the suspect's DNA will be added following PCR amplification.
C)PCR will be used to make sequence-specific primers that are complementary to the suspect's DNA.
D)Since multiple people touched the doorknob without gloves,it is impossible to use PCR to distinguish the suspect's DNA.

Question 15

Which situation(s)might warrant the removal of a histidine tag when purifying a recombinant protein?

A)Histidine residues inhibit protein folding,thereby decreasing the functionality of the protein.
B)Histidine residues bind preferentially to nickel resins on the column during purification,and are not washed away.
C)The expression vector used for inserting the gene of interest already contains histidine-encoding sequences.
D)All of the choices are correct.

Question 16

A microbiologist would like to use a noncompetent genus of streptococcal bacteria,Enterococcus faecalis,as a cloning host to express genes from Streptococcus pneumoniae,which is naturally competent.Is this possible?

A)Yes; electroporation or chemical transformation can be used to make Enterococcus competent,and then genes from Streptococcus can be introduced via a cloning vector.
B)Yes; electroporation or chemical transformation can be used to make non-competent Streptococcus mutants,from which genes can be inserted into a cloning vector and introduced into Enterococcus.
C)No; competence factor is an essential protein that enables the uptake of foreign DNA,therefore a cloning host such as Enterococcus that lacks competence factor protein is unable to be transformed by electroporation or chemical transformation.
D)Yes; since the cloning host and the DNA to be introduced are both from bacteria that are streptococci,natural competence in this case is not necessary as long as the appropriate vector is used.

Question 17

A genomic __________ is a sufficiently large collection of recombinant DNA molecules in which the inserted sequences together represent the entire genome of an organism.

Question 18

Which of the following techniques exemplifies phenotypic rescue in a host cell?

A)Introducing a genomic library from a cell that produces a particular gene product into a mutant host cell auxotroph that cannot synthesize the product.
B)Introducing a genomic library from a mutant cell auxotroph for a particular gene product into a host cell that can synthesize that product constitutively.
C)Removing genes that encode a particular gene product from a cell that expresses that product constitutively before creating a genomic library.
D)Replacing a mutant gene with a functional gene in a DNA library from an auxotrophic mutant cell prior to introducing the library into a related host cell.

Question 19

In _____________,cells are mixed with recombinant DNA and exposed to a brief pulse of high-voltage electricity to cause the membrane to become permeable and allow the uptake of DNA from its environment.

Question 20

Promoters for genes that code for proteins can be isolated from a cDNA library.

Question 21

Which of the following types of cloning vector can carry the largest amount of foreign DNA?

A)bacterial artificial chromosome
B)bacteriophage
C)cosmid
D)plasmid

Question 22

A (n)__________ vector is a plasmid that can be replicated in several different organisms because it has at least one origin of replication that will function in each host.

A)shuttle
B)chimeric
C)expression
D)phage

Question 23

Transposons are frequently used as cloning vectors.

Question 24

Which of the following is not true of cloning vectors?

A)They usually contain multicloning sites or polylinkers.
B)They contain at least two replication origins.
C)They can be replicated within an appropriate host.
D)All of these are true of cloning vectors.

Question 25

Cloning a gene involves all of the following except

A)isolating the fragment of DNA containing the desired gene.
B)insertion of the gene into an appropriate vector.
C)expression of the vector and the gene in a cell-free environment.
D)introducing ligated DNA into
E)coli cells.

Question 26

A(n)__________ __________ is a piece of DNA with all of the features necessary for chromosomal replication and which can carry large (up to 1000 kb)pieces of foreign DNA into a host organism.

Question 27

Plasmid vectors often contain __________ genes that can be used to screen for recombinants.

A)metabolic activation
B)antibiotic resistance
C)insertion sequence
D)promoter/operator

Question 28

Antibiotics incorporated into the culture medium can

A)select against organisms that have not incorporated the plasmid.
B)select against organisms that have incorporated a plasmid not containing the desired gene.
C)enhance production of recombinant proteins.
D)select against organisms that have not incorporated the plasmid and select against organisms that have incorporated a plasmid not containing the desired gene

Question 29

If all of the PCR products of a DNA sequence are 4000 bp,then the DNA sequence that was amplified must have been 8000 bp.

Question 30

A DNA molecule used to carry a foreign gene into a host organism is called a

A)plasmid.
B)vector.
C)probe.
D)blot.

Question 31

Which is a true statement regarding the size of PCR products?

A)Since the number of DNA products ending exactly between both primers increases with each cycle,when PCR is completed,the majority of products are of similar size.
B)Since the number of DNA products extends beyond each primer with each cycle,when PCR is completed,the majority of products are of various sizes.
C)Since the length of primers increases with each cycle,when PCR is completed,the majority of products are of various sizes.
D)None of the choices are correct.

Question 32

One of the major advantages to using plasmids as cloning vectors is that very high copy numbers can be achieved with many types of plasmid vectors.

Question 33

Which of the following is not part of a yeast artificial chromosome (YAC)?

A)the F factor
B)a selectable marker
C)an ARS
D)a CEN sequence

Question 34

Which of the following PCR procedures includes all of the others?

A)DNA is amplified for one cycle.
B)DNA is denatured at 95^oC.
C)DNA is reannealed at 50^oC
D)Primers are extended at 72^oC.

Question 35

The production of large quantities of a particular DNA sequence is known as gene __________________.

Question 36

___________ is a bacterial plasmid vector.

A)Lambda
B)T4 DNA ligase
C)pUC19
D)SV40

Question 37

Which of the following can be used as vectors for cloning DNA fragments?

A)plasmids
B)cosmids
C)bacteriophages
D)All of the choices are correct.

Question 38

Cosmids are so named because they can be used to express foreign genes in a variety of different hosts.

Question 39

Cosmids are plasmids that can be packaged into capsids of the bacteriophage lambda; therefore,they can be transmitted like phages,but they can exist and replicate in a cell like plasmids.

Question 40

Plasmid cloning vector DNA is usually introduced into bacterial hosts by

A)ligation.
B)transformation.
C)transduction.
D)plasmolysis.

Question 41

When a eukaryotic gene is cloned into a bacterium,the advantage of a complementary DNA (cDNA)gene being used instead of fragments of genomic DNA is that

A)the promoter and terminator are found in the cDNA gene but not in the genomic fragment.
B)the introns have been removed from the cDNA gene but not from the genomic fragment.
C)the cDNA is made with the nucleotides found in the prokaryote but not in the eukaryote.
D)There is no advantage to using a cDNA gene rather than a genomic fragment.

Question 42

The Southern blotting technique for transferring DNA from an agarose gel to a piece of nitrocellulose membrane is named for

Question 43

Sputum from a patient with a history of tuberculosis due to Mycobacterium tuberculosis bacteria is collected and sent to the microbiology lab for analysis.X-ray analysis and an acid-fast smear made from the sputum indicate that the patient has active tuberculosis.The physician has requested that the sputum be analyzed for pathogen load,but because colonies of Mycobacterium typically take between 3 to 8 weeks to appear on agar,results from traditional culture methods are often delayed.If you were the microbiologist in this case,what would you do?

A)Using the sputum,apply real-time PCR with primers to Mycobacterium tuberculosis DNA to estimate the pathogen load,then follow up with a traditional culture.
B)Using the sputum,apply end-point PCR with primers to Mycobacterium tuberculosis DNA to estimate the pathogen load,then follow up with a traditional culture.
C)Set up a traditional culture on the sputum,then use the colonies for real-time PCR with primers to Mycobacterium tuberculosis DNA to quantify the pathogen load.
D)Set up a traditional culture on the sputum,then use the colonies for end-point PCR with primers to Mycobacterium tuberculosis DNA to quantify the pathogen load.

Question 44

The thermostable enzyme most commonly used in PCR is reverse transcriptase.

Question 45

An enzyme that cleaves internal phosphodiester bonds of a DNA molecule is a (n)

A)exonuclease.
B)endonuclease.
C)ligase.
D)methylase.

Question 46

A PCR procedure that allows a determination of the amount of a particular DNA fragment that is present in a sample is called

A)quantitative PCR.
B)analytical PCR.
C)real-time PCR.
D)reverse PCR.

Question 47

Restriction endonucleases in bacteria may have evolved in order to

A)carry out natural genetic engineering.
B)protect the bacteria from infection by viruses.
C)use nucleic acids as a food (energy)source.
D)All of the choices are correct.

Question 48

Which procedure is most useful in quantifying the active transcription of botulism toxin genes in a can of food that is contaminated?

A)Southern blot
B)End-point PCR
C)Real-time PCR
D)DNA hybridization

Question 49

If DNA were a positively charged rather than negatively charged,what change to the gel electrophoresis procedure must be made?

A)DNA must be loaded at the positive pole rather than at the negative pole.
B)Migration time of restriction fragments must be increased.
C)Type of buffer used must be basic rather than neutral.
D)All of the choices are correct.

Question 50

Plasmid DNA having one EcoRI recognition sequence is treated with EcoRI restriction endonuclease.Following gel electrophoresis,how many bands should be visible on the gel?

A)One
B)Two
C)Four
D)Zero

Question 51

When separating DNA fragments by gel electrophoresis,what is the purpose of including molecular weight markers?

A)Markers are used as a control to determine the relative size of restriction fragments.
B)Markers provide an indication as to the total number of restriction fragments on the gel.
C)Markers are needed to estimate the relative charges on each of the restriction fragments.
D)Markers ensure that fragments having a greater molecular weight migrate at the same rate as those having a lighter molecular weight.

Question 52

The polymerase chain reaction (PCR)can be used to produce __________ of copies in a few hours.

A)hundreds
B)thousands
C)millions
D)billions

Question 53

The three steps that take place in each cycle during PCR occur in which order?

A)DNA annealing,denaturation,and synthesis
B)DNA denaturation,annealing,and synthesis
C)DNA synthesis,denaturation,and annealing
D)None of the choices are correct.

Question 54

A molecular biologist treats a 600-kb length of linear DNA with HindIII restriction endonuclease.Following gel electrophoresis,the biologist observes that there is only one band on the gel corresponding with the migration distance of the 200-kb molecular weight marker.Assuming that no procedural errors were made,what can be concluded from these results?

A)Two HindIII recognition sequences were present in the original DNA.
B)Three HindIII recognition sequences were present in the original DNA.
C)There were no HindIII recognition sequences present in the original DNA.
D)One HindIII recognition sequence was present in the original DNA.

Question 55

A __________ is a DNA molecule used in hybridization reactions to detect the presence of a particular gene in separated DNA fragments.

A)plasmid
B)vector
C)probe
D)blot

Question 56

Recombinant DNA technology does not rely on which of the following enzymes?

A)restriction endonucleases
B)RNA methylase
C)DNA ligase
D)reverse transcriptase

Question 57

The PCR method was developed by

A)Boyer.
B)Mullis.
C)Cohen.
D)Sanger.

Question 58

If all of the restriction fragments in a DNA digest were of very low molecular weight,then all of the fragments on the electrophoretic gel will be closest to the positive pole and furthest from the negative pole.

Question 59

Complementary DNA (cDNA)probes are produced using

A)restriction endonucleases.
B)RNA polymerase.
C)DNA ligase.
D)reverse transcriptase.

Question 60

Which of the following is true about restriction endonucleases?

A)They make a blunt cut on the two DNA strands so that there are no single-strand regions.
B)They make staggered cuts on the DNA so that single-strand ends are formed that can be used to insert foreign DNA cut with the same enzyme.
C)Some make a blunt cut on the two DNA strands so that there are no single-strand regions and some make staggered cuts on the DNA so that single-strand ends are formed that can be used to insert foreign DNA cut with the same enzyme.
D)Depending on the incubation conditions,the same enzyme can either make a blunt cut on the two DNA strands so that there are no single-strand regions OR make staggered cuts on the DNA so that single-strand ends are formed that can be used to insert foreign DNA cut with the same enzyme.

Question 61

In order to express eukaryotic genes in a bacterium,the __________ must first be removed.

A)introns
B)exons
C)enhancers
D)3' poly A sequence

Question 62

Which of the following was first produced commercially using recombinant DNA technology?

A)human growth hormone
B)interleukins
C)hepatitis B vaccine
D)human insulin

Question 63

The enzyme reverse transcriptase was discovered by

A)Arber and Smith.
B)Jackson,Symons,and Berg.
C)Boyer and Cohen.
D)Temin and Baltimore.

Question 64

Which is the most frequently chosen prokaryotic host for use in cloning techniques?

A)Saccharomyces cerevisiae
B)Bacillus subtilis
C)Staphylococcus aureus
D)Escherichia coli

Question 65

Electroporation is commonly used to introduce recombinant DNA molecules into cells.

Question 66

Which of the following best describes the basis for separation of DNA fragments during agarose gel electrophoresis?

A)The fragments with the highest percentage of G and C will migrate fastest.
B)The fragments with the highest percentage of A and T will migrate fastest.
C)The largest fragments will migrate fastest.
D)The smallest fragments will migrate fastest.

Question 67

Restriction endonucleases were discovered by

A)Arber and Smith.
B)Jackson,Symons,and Berg.
C)Boyer and Cohen.
D)Temin and Baltimore.

Question 68

Genetic engineering methods have been used to produce vaccines.

Question 69

Restriction endonucleases are produced by

A)fungi.
B)bacteria.
C)protozoa.
D)plants.
E)All of the choices are correct.

Question 70

Movement of charged molecules in an electrical field,which is used to separate nucleic acid fragments for recombinant DNA work,is called

A)iontophoresis.
B)nucleophoresis.
C)electrophoresis.
D)plasmaphoresis.