Deck 19: Analyzing and Engineering Genes

Question 1

What is a primary difference between PCR and traditional cloning procedures such as those used to clone the human growth hormone gene?

A)PCR and traditional cloning make use of different types of bacteria.
B)PCR and traditional cloning make use of different types of vectors.
C)PCR uses plasmid vectors,whereas traditional cloning uses bacteria.
D)PCR eliminates the need for restriction enzymes,vectors,and cells.
E)PCR is more time-consuming,but the purity of the obtained DNA clone is much higher than in traditional cloning.

Answer 1

D

Question 2

Imagine that you've prepared a Southern blot and probed it using a single probe.You observe 8 different bands after autoradiography,with one band being very dark and the other 7 being significantly lighter.What is suggested by these results?

A)The gene recognized by the probe has been cut into eight different fragments by the restriction enzyme.
B)The probe has been cut into eight different fragments by the restriction enzyme.
C)There are eight similar genes in the genome.
D)The DNA did not transfer from the gel to the nylon filter.
E)The DNA remained double stranded on the blot.

Answer 2

C

Question 3

Plasmids are used as cloning vectors in genetic engineering.This means that plasmids allow for

A)carrying of DNA into a cell and DNA replication.
B)infection of cells.
C)DNA replication outside rather than inside cells.
D)carrying of RNA into a cell and RNA replication.

Answer 3

A

Question 4

How does a gene library differ from a gene clone?

A)A gene library contains many different cloned DNA sequences;a gene clone contains one type of DNA sequence.
B)A gene library contains one type of cloned DNA sequence;a gene clone contains many different DNA sequences.
C)A gene library is a much longer DNA sequence than a gene clone.
D)A gene library is a much shorter DNA sequence than a gene clone.
E)A gene library is sequence information stored in a computerized database;a gene clone is an actual sequence of DNA.

Question 5

Figure 19.2
The answer set for this question shows a series of short amino acid sequences obtained from a protein.If you were faced with choosing one of these to design a probe for a particular gene,which would provide the simplest probe or probe set? (To answer this question,consult the codon table shown in the figure above ).

A)leucine-leucine-serine-leucine
B)leucine-serine-proline-proline
C)proline-methionine-proline-leucine
D)tryptophan-methionine-tryptophan-tryptophan

Question 6

Which of following sequences is most likely to be cut by a restriction enzyme?

A)AATCGT TTACGA
B)AATTCT TTAAGA
C)AATATT TTATAA
D)AAAATT TTTTAA
E)ACTACT TGATGA

Question 7

Many identical copies of genes cloned in bacteria are produced as a result of

A)plasmid replication.
B)bacterial cell replication.
C)Southern blotting.
D)A and B.
E)all of the above.

Question 8

A bacterial cell that has taken up plasmid DNA is

A)transformed.
B)ligated.
C)a library.
D)a cDNA.
E)a vector.

Question 9

How can an amino acid sequence be used to design a gene-specific hybridization probe?

A)A portion of a polypeptide chain can be synthesized based on the amino acid sequence of the full protein.
B)A protein can be purified,digested with proteases that cleave it at specific sites,and one of the peptide fragments can be used as a probe.
C)All possible nucleotide sequences that could encode a portion of the polypeptide can be synthesized and used as probes.

Question 10

The general term for the manipulation of organisms to create products or cure disease is

A)recombinant DNA technology.
B)biotechnology.
C)gene cloning.
D)plasmid-mediated transformation.

Question 11

If mRNAs could be ligated and replicated within plasmids,what enzyme commonly used in recombinant DNA technology would no longer be needed?

A)restriction enzymes
B)DNA polymerase
C)reverse transcriptase
D)Taq polymerase

Question 12

Imagine that you've isolated the complete human growth hormone gene directly from the human genome.After running through all the steps described in Chapter 19 for cloning and gene expression in bacteria,you find that no human growth hormone is expressed.What is the most likely explanation?

A)Human DNA cannot be cloned in a bacterium.
B)Human DNA can be maintained in cloned form only for brief periods in bacteria.
C)Bacteria cannot translate human mRNA coding sequences.
D)Bacteria cannot carry out splicing.
E)Bacteria lack a nucleus for proper transcription of eukaryotic genes.

Question 13

In a single PCR cycle consisting of 15 seconds at 94°C,30 seconds at 50°C,and 1 min at 72°C,what is happening in the step run at 50°C?

A)The DNA to be amplified is being denatured.
B)Primers are being denatured.
C)DNA polymerase is extending new DNA from the primers.
D)Primers are annealing to the DNA to be amplified.
E)DNA polymerase is being inactivated.

Question 14

The restriction enzymes BamHI and BclI cut at the points indicated by arrows:
If one sample of DNA was cut with BamHI and another with BclI,and these two samples were mixed and treated with DNA ligase,what would occur?

A)No DNAs would be ligated (joined together).
B)Only the BamHI-cut DNA would be ligated.
C)Only the BclI-cut DNA would be ligated.
D)Both BamHI-cut and BclI-cut DNAs would be ligated,but only to DNA fragments cut with the same enzyme (e.g.,BamHI fragments would be ligated only to other BamHI fragments).
E)Both BamHI-cut and BclI-cut DNAs would be ligated with no preference for which fragment is ligated to which other.

Question 15

Which of the following is a gene library?

A)a collection of DNAs cut by a restriction enzyme
B)a collection of plasmids cut by a restriction enzyme
C)a collection of different DNA fragments ligated into plasmids
D)a collection of genes that have been sequenced from a particular organism
E)a collection of PCR-amplified DNAs

Question 16

In early forensic applications of DNA fingerprinting,DNA was extracted from crime scene material,digested with restriction enzymes,and then used to prepare a Southern blot.Today,PCR is used in the early steps of forensic DNA analysis.What advantage does PCR provide over the former method?

A)PCR produces many more bands for fingerprint analysis,making it a more informative technique.
B)PCR can cut DNA at many more sites than restriction enzymes can.
C)PCR requires much less DNA for analysis.
D)PCR can analyze DNA,proteins,and carbohydrates,whereas restriction enzyme analysis is limited to DNA.

Question 17

The final step in a DNA sequencing reaction is to run the DNA fragments on a gel.What purpose does this serve?

A)It provides the substrate for DNA polymerase.
B)It separates dideoxynucleotides from deoxynucleotides.
C)It terminates the sequencing reaction at particular bases.
D)It separates DNA fragments generated during the sequencing reaction based on one-nucleotide differences in their size.

Question 18

What information is critical to the success of PCR itself?

A)The DNA sequence of the ends of the DNA to be amplified must be known.
B)The complete DNA sequence of the DNA to be amplified must be known.
C)The sequence of restriction enzyme recognition sites in the DNA to be amplified must be known.
D)The sequence of restriction enzyme recognition sites in the DNA to be amplified and in the plasmid where the amplified DNA fragment will be cloned must be known.

Question 19

When constructing a cDNA library from a particular organism,the choice of tissue is ________,whereas when constructing a genomic DNA library from the same organism,the choice of tissue is ________.

A)critical;critical
B)immaterial;immaterial
C)immaterial;critical
D)critical;immaterial

Question 20

Which of the following is in the correct order for one cycle of PCR?

A)Denature DNA;add fresh enzyme;anneal primers;add dNTPs;extend primers.
B)Add fresh enzyme;denature DNA;anneal primers;add dNTPs;extend primers.
C)Anneal primers;denature DNA;extend primers.
D)Extend primers;anneal primers;denature DNA.
E)Denature DNA;anneal primers;extend primers.

Question 21

Why might retroviral vectors for gene therapy increase the patient's risk of developing cancer?

A)They might fail to introduce genes into any of the patient's cells.
B)They might not express the genes that were introduced into a patient's cells.
C)They might not integrate their recombinant DNA into the patient's genome.
D)They might integrate recombinant DNA into the genome in ways that misregulate the expression of genes at or near the site of integration.

Question 22

Imagine that you compare two DNA sequences found in the same location on homologous chromosomes.On one of the homologs,the sequence is AACTACGA.On the other homolog,the sequence is AACTTCGA.Within a population,you discover that each of these sequences is common.These sequences

A)contain a SNP that may be useful for genetic mapping.
B)identify a protein-coding region of a gene.
C)cause disease.
D)protect against disease.
E)none of the above.

Question 23

In the current form of dideoxy DNA sequencing,the primer is unlabeled and each dideoxynucleotide is labeled with a different fluorescent marker.This method

A)eliminates the need to run sequencing reaction products on a gel.
B)allows a DNA sequence to be determined from 4 separate sequencing reactions,each run on a separate lane of a gel.
C)allows a DNA sequence to be determined from one sequencing reaction that is run on a single lane of a gel.
D)eliminates the need for sophisticated machines to read the output of each sequencing reaction.

Question 24

Genetically engineered crops in the United States

A)may soon be ready for commercial planting.
B)have seen some limited commercial success.
C)are currently available only for rice.
D)are widespread for many major crop species.
E)are the only types of crops now being planted.

Question 25

How could the "demographic history of Neanderthal populations" be explored if mitochondrial DNA from other Neanderthal samples could be PCR amplified?

A)These Neanderthal sequences could be compared to those of modern humans to learn if they are closely related.
B)These Neanderthal sequences could be compared to those of modern humans;the more they differ,the more distant the time of divergence between the Neanderthal and modern human lineages.
C)These Neanderthal sequences could be compared to each other to see how much they differ;the more they differ,the greater the divergence between these populations.
D)In the attempt to amplify other Neanderthal DNAs,those that amplify must be from more modern populations and those that don't are from more ancient populations.

Question 26

Plasmids are used as vectors in both plant and bacterial genetic engineering.However,there is a major difference in the fate of genes introduced into bacteria on most bacterial plasmids and into plants on Ti plasmids.What is this difference?

A)In bacteria,genes are stably expressed;in plants,gene expression is always lost quickly.
B)Gene expression tends to decrease rapidly and unpredictably in bacteria;gene expression is much more stable in plants.
C)Bacterial plasmids are circular DNAs;Ti plasmid DNA is linear.
D)Bacterial plasmids and the genes they carry usually are not integrated into the chromosome;Ti plasmids and the genes they carry are integrated into the chromosome.
E)Bacterial plasmids typically do not modify the growth of the host cells;Ti plasmids modified for genetic engineering always produce plant galls.

Question 27

Gene therapy requires

A)knowledge and availability of the wild-type allele of the defective gene.
B)an ability to introduce the wild-type allele into the patient.
C)an ability to express the introduced gene at the correct level,time,and site within the patient.
D)A and B.
E)all of the above.

Question 28

Why is it essential that genetic markers used in mapping disease genes be polymorphic?

A)If the marker isn't polymorphic,its position cannot be known.
B)If the marker isn't polymorphic,it cannot be physically linked to a gene associated with human disease.
C)If the marker isn't polymorphic,then it will not be inherited in any predictable manner.
D)If the marker isn't polymorphic,then it's impossible to use genetic mapping techniques to establish an association between the marker and the disease gene.

Question 29

One example of an innovation from an unexpected source comes from studies of tumor-like plant growths.What information did the study of plant tumors provide that was critical for plant genetic engineering?

A)understanding the role of plant hormones in growth promotion
B)knowledge of plant tumor suppressor and proto-oncogenes
C)learning that metastasis is critical for tumor progression
D)learning the biosynthetic pathway to β-carotene
E)discovery of a plasmid that could be modified to introduce genes into plants

Question 30

To create a viral vector for delivery of genes into mammalian cells,the virus must be engineered to

A)remove viral coat proteins.
B)remove all viral genes,replacing them with the mammalian genes to be delivered.
C)remove viral genes involved with virus replication and add mammalian genes to be delivered.
D)remove the viral genome and coat proteins and replace them with recombinant plasmids carrying the mammalian genes to be delivered.

Question 31

The areas that have received the greatest attention in genetically modified plants are

A)improved product quality and increased pest and herbicide resistance.
B)improved product quality,more rapid growth through plant hormone production,and decreased herbicide resistance.
C)more rapid growth through plant hormone production,pharmaceutical production,and increased antibiotic resistance.
D)pharmaceutical production,production of useful compounds not normally found in nature (xenobiotics),and the ability to remove or neutralize toxic compounds from the environment (bioremediation).

Question 32

The genes needed for β-carotene synthesis are not normally expressed in endosperm.In the creation of golden rice,how did researchers ensure that these genes were expressed in rice endosperm?

A)The genes were injected only in the endosperm of rice grains.
B)Agrobacterium cells were added only to rice grains,not to any other part of the plant.
C)The protein-coding sequence of each gene was linked to a regulatory region of DNA that directed transcription in endosperm.
D)The wild-type genes were mutated and new mutant alleles that are expressed only in endosperm were selected.

Question 33

In the form of gene therapy used successfully for severe combined immunodeficiency syndrome (SCID)-X1,the genetic engineering of human cells is done

A)by injecting engineered viruses into the patient's bloodstream.
B)by injecting engineered viruses into the patient's bone marrow.
C)by treating a relative's cultured bone marrow cells with genetically engineered viruses and then injecting these cells into the patient's bone marrow.
D)by isolating the patient's bone marrow cells,infecting them with genetically engineered viruses,and injecting them back into the patient's bone marrow.

Question 34

Since dideoxy sequencing is based on the chain termination,why are normal deoxynucleotides also included in the reaction?

A)to enhance the chain termination ability of the deoxynucleotides
B)to provide a substrate for DNA polymerase
C)to produce a range of DNA synthesis products that terminate at every occurrence of a particular base
D)to create DNA synthesis products long enough to allow running a gel

Question 35

If you are a human geneticist looking for an ideal population in which to map disease genes,what characteristic would you want this population to possess?

A)large family size
B)good medical records
C)well-established genealogy stretching back many generations
D)individuals interested and willing to participate in genetic studies
E)all of the above

Question 36

Why did the researchers wear protective clothing and note so emphatically that they did so?

A)They needed to be certain there were no ancient pathogens on the sample that modern humans hadn't been exposed to.
B)They needed to be sure not to harm the precious sample with oils from skin or moisture from their breath.
C)They needed to minimize the chance of introducing their own mitochondrial DNA to the sample.
D)Because the work was done in Germany,they needed to follow stringent,standard German laboratory procedures and document their compliance.

Question 37

Transgenic mice

A)often provide valuable animal models of human disease.
B)are essential for mapping human genes.
C)are now used in place of bacteria for cloning human genes.
D)were instrumental in pinpointing the location of the huntingtin gene.

Question 38

Which type of disorder is most difficult to correct by gene therapy?

A)a dominant disorder
B)an incompletely dominant disorder
C)a recessive disorder
D)Disorders showing all these forms of dominance present equal challenges.

Question 39

For applications in gene therapy,what is the most favorable characteristic of retroviruses?

A)Retroviruses have an RNA genome.
B)Retroviruses possess reverse transcriptase.
C)DNA copies of retroviral genomes become integrated into the genome of the infected cell.
D)Retroviruses cause many serious diseases,including AIDS and cancer.

Question 40

Imagine that you are searching for the gene associated with nail-patella syndrome,a dominant genetic disorder that causes developmental abnormalities.In a large pedigree,you discover an association between nail-patella syndrome and a genetic marker that occurs in two different alleles,A and B.Fifteen individuals within this pedigree have nail-patella syndrome and are A/B heterozygotes for the marker.Thirty individuals within this pedigree don't suffer from nail-patella syndrome and are homozygous for the A marker allele.One individual within this pedigree has nail-patella syndrome and is also homozygous for the A marker allele.The most likely explanation for this exceptional individual is

A)a new mutation converted the disease-causing allele to the wild-type form.
B)a new mutation converted the B allele of the marker to the A form.
C)the exceptional nail-patella individual is haploid.
D)recombination occurred between the nail-patella gene and marker gene in one of the parents of the exceptional individual.

Question 41

You ask your student to transfer a plasmid-free bacterial strain to multiple small tubes for long term storage.A short while later,your student admits that he did not use a clean sterile pipette to transfer the bacteria to the small tubes,but rather grabbed the same pipette he had just used to collect newly transformed bacteria.Why would this pose a problem?

A)Plasmids can be transferred between bacteria via pili.
B)Newly transformed bacteria will actively undergo binary fission.
C)Plasmid can contain genes that confer antibiotic resistance.
D)Plasmids will incorporate into the chromosomal DNA.