EXAM 4: QUIZ METHODS: DNA Flashcards
Genetically engineered plants
include a transgenic rice plant that can help prevent vitamin A deficiency.
Which of the following procedures would produce RFLPs?
incubating DNA with restriction enzymes
In recombinant DNA methods, the term vector can refer to
a plasmid used to transfer DNA into a living cell.
Sequencing an entire genome, such as that of C. elegans, a nematode, is most important because
a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates.
How does a genomic library differ from a cDNA library?
g 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.
Imagine you want to study human crystallins, proteins present in the lens of the eye. To obtain a sufficient amount of the protein, you decide to clone the crystallin gene. Would you construct a genomic library or a cDNA library? What material would you use as a source of DNA or RNA?
mRNA from human lens cells
Which of the following best describes the complete sequence of steps occurring during every cycle of PCR? 1. The primers hybridize to the target DNA. 2. The mixture is heated to a high temperature to denature the double stranded target DNA. 3. Fresh DNA polymerase is added. 4. DNA polymerase extends the primers to make a copy of the target DNA.
2, 1, 4
To introduce a particular piece of DNA into an animal cell, such as that of a mouse, you would find more probable success with which of the following methods?
electroporation followed by recombination
Which of the following is true of embryonic stem cells but not of adult stem cells?
They make up the majority of cells of the tissue from which they are derived.
Which uses reverse transcriptase to make cDNA followed by amplification?
RT-PCR
CML (chronic myelogenous leukemia) results from a translocation between human chromosomes 9 and 22. The resulting chromosome 22 is significantly shorter than the usual, and it is known as a Philadelphia (Ph’) chromosome. The junction at the site of the translocation causes over-expression of a thymine kinase receptor. A new drug (Gleevec or imatinib) has been found to inhibit the disease if the patient is treated early. Why would Gleevec most probably cause remission of the disease?
The drug inhibits the specific thymine kinase receptor.
In 1997, Dolly the sheep was cloned. Which of the following processes was used?
fusion of an adult cell’s nucleus with an enucleated sheep egg, followed by incubation in a surrogate
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 do not take up any plasmids would grow on which media?
the nutrient broth only
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.
III, II, IV, V, I
Expression of a cloned eukaryotic gene in a bacterial cell involves many challenges. The use of mRNA and reverse transcriptase is part of a strategy to solve the problem of
post-transcriptional processing.
Which was developed by a British researcher and causes DNA sequences to be transferred to a membrane and identified with a probe?
Southern blotting
DNA microarrays have made a huge impact on genomic studies because they
allow the expression of many or even all of the genes in the genome to be compared at once.
Which of the following techniques used to analyze gene function depends on the specificity of DNA base complementarity?
in vitro mutagenesis
Which seals the sticky ends of restriction fragments to make recombinant DNA?
DNA ligase
Which of the following separates molecules by movement due to size and electrical charge?
gel electrophoresis
Which of the following is one of the technical reasons why gene therapy is problematic?
Transferred genes may not have appropriately controlled activity.
Imagine you want to study human crystallins, proteins present in the lens of the eye. To obtain a sufficient amount of the protein, you decide to clone the crystallin gene. Would you construct a genomic library or a cDNA library?
cDNA library
Which of the following is used to make complementary DNA (cDNA) from RNA?
reverse transcriptase
Gene therapy
had apparent success in treating disorders involving bone marrow cells.
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 containing a plasmid into which the eukaryotic gene has integrated would grow in
the ampicillin broth and the nutrient broth.
Which of the following cuts DNA molecules at specific locations?
restriction enzymes
CML (chronic myelogenous leukemia) results from a translocation between human chromosomes 9 and 22. The resulting chromosome 22 is significantly shorter than the usual, and it is known as a Philadelphia (Ph’) chromosome. The junction at the site of the translocation causes over-expression of a thymine kinase receptor. A new drug (Gleevec or imatinib) has been found to inhibit the disease if the patient is treated early. Which of the following would be a reasonably efficient technique for confirming the diagnosis of CML?
in situ hybriditation-FISH study to determine the chromosomal location of all chromosome 22 q fragments
Plants are more readily manipulated by genetic engineering than are animals because
a somatic plant cell can often give rise to a complete plant.
The DNA fragments making up a genomic library are generally contained in
recombinant plasmids of bacteria.
Which describes the transfer of polypeptide sequences to a membrane to analyze gene expression?
Western blotting
One successful form of gene therapy has involved delivery of an allele for the enzyme adenosine deaminase (ADA) to bone marrow cells of a child with SCID, and delivery of these engineered cells back to the bone marrow of the affected child. What is one major reason for the success of this procedure as opposed to many other efforts at gene therapy?
engineered cells, when reintroduced into the patient, find their way back to the bone marrow.
DNA technology has many medical applications. Which of the following is not done routinely at present?
introduction of genetically engineered genes into human gametes
Genetic engineering is being used by the pharmaceutical industry. Which of the following is not currently one of the uses?
creation of products that will remove poisons from the human body
RNAi methodology uses double-stranded pieces of RNA to trigger a breakdown or blocking of mRNA. For which of the following might it more possibly be useful?
to decrease the production from a harmful gain-of-function mutated gene
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
cut DNA again with RE Y and insert these fragments into the plasmid cut with the same enzyme.
A paleontologist has recovered a bit of tissue from the 400-year-old preserved skin of an extinct dodo (a bird). The researcher would like to compare a specific region of the DNA from the sample with DNA from living birds. Which of the following would be most useful for increasing the amount of dodo DNA available for testing
polymerase chain reaction (PCR)
Which of the following is most closely identical to the formation of twins?
organismal cloning
DNA fragments from a gel are transferred to a nitrocellulose paper during the procedure called Southern blotting. What is the purpose of transferring DNA from a gel to a nitrocellulose paper?
to attach the DNA fragments to a permanent substrate
Why are yeast cells frequently used as hosts for cloning?
they are eukaryotic cells
Restriction fragments of DNA are typically separated from one another by which process?
gel electrophoresis
What is the enzymatic function of restriction enzymes?
to cleave nucleic acids at specific sites
Reproductive cloning of human embryos is generally considered unethical. However, on the subject of therapeutic cloning there is a wider divergence of opinion. Which of the following is a likely explanation?
Cloning to produce embryonic stem cells may lead to great medical benefits for many.
Scientists developed a set of guidelines to address the safety of DNA technology. Which of the following is one of the adopted safety measures?
Correct Microorganisms used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside of the laboratory.
How does a bacterial cell protect its own DNA from restriction enzymes?
adding methyl groups to adenines and cytosines
A student wishes to clone a sequence of DNA of ~200 kb. Which vector would be appropriate?
a BAC
Which of the following would not be true of cDNA produced using human brain tissue as the starting material?
It could be used to create a complete genomic library.
A principal problem with inserting an unmodified mammalian gene into a bacterial plasmid, and then getting that gene expressed in bacteria, is that
bacteria cannot remove eukaryotic introns.
Which problems with animal cloning might result in premature death of the clones?
abnormal regulation due to variant methylation
A researcher has used in vitro mutagenesis to mutate a cloned gene and then has reinserted this into a cell. In order to have the mutated sequence disable the function of the gene, what must then occur?
recombination resulting in replacement of the wild type with the mutated gene
Which of the following tools of recombinant DNA technology is incorrectly paired with its use?
DNA ligase-enzyme that cuts DNA, creating the sticky ends of restriction fragments
In order to identify a specific restriction fragment using a probe, what must be done?
- the fragments must be separated by electrophoresis
- fragments must be treated with heat or chemicals to separate the strands of the double helix
- the probe must be hybridized with the fragments
Which of the following modifications is least likely to alter the rate at which a DNA fragment moves through a gel during electrophoresis?
altering the nucleotide sequence of the DNA fragment
A researcher needs to clone a sequence of part of a eukaryotic genome in order to express the sequence and to modify the polypeptide product. She would be able to satisfy these requirements by using which of the following vectors?
a YAC with appropriate cellular enzymes
As genetic technology makes testing for a wide variety of genotypes possible, which of the following is likely to be an increasingly troublesome issue?
the need to legislate for the protection of the privacy of genetic information
Bacteria containing recombinant plasmids are often identified by which process?
exposing the bacteria to an antibiotic that kills cells lacking the resistant plasmid
RFLP (Restriction fragment length polymorphism) analysis can be used to distinguish between alleles based on differences in which of the following?
restriction enzyme recognition sites between the alleles
One possible use of transgenic plants is in the production of human proteins, such as vaccines. Which of the following is a possible hindrance that must be overcome?
prevention of transmission of plant allergens to the vaccine recipients
Dideoxyribonucleotide chain-termination is a method of
sequencing DNA.
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 not the eukaryotic gene, would grow
in all four types of broth.
Which of the following produces multiple identical copies of a gene for basic research or for large-scale production of a gene product?
gene cloning
A researcher is using adult stem cells and comparing them to other adult cells from the same tissue. Which of the following is a likely finding?
The cells from the two sources exhibit different patterns of DNA methylation.
A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using
reverse transcriptase to reconstruct the gene from its mRNA.
Yeast artificial chromosomes contain which of the following elements?
centromere, telomeres, and an origin of replication
The major advantage of using artificial chromosomes such as YACs and BACs for cloning
genes is that
YACs and BACs can carry much larger DNA fragments than ordinary plasmids can.
