EXAM 4: QUIZ METHODS: DNA

Question 1

Genetically engineered plants

Answer 1

include a transgenic rice plant that can help prevent vitamin A deficiency.

Question 2

Which of the following procedures would produce RFLPs?

Answer 2

incubating DNA with restriction enzymes

Question 3

In recombinant DNA methods, the term vector can refer to

Answer 3

a plasmid used to transfer DNA into a living cell.

Question 4

Sequencing an entire genome, such as that of C. elegans, a nematode, is most important because

Answer 4

a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates.

Question 5

How does a genomic library differ from a cDNA library?

Answer 5

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.

Question 6

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?

Answer 6

mRNA from human lens cells

Question 7

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.

Answer 7

2, 1, 4

Question 8

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?

Answer 8

electroporation followed by recombination

Question 9

Which of the following is true of embryonic stem cells but not of adult stem cells?

Answer 9

They make up the majority of cells of the tissue from which they are derived.

Question 10

Which uses reverse transcriptase to make cDNA followed by amplification?

Answer 10

RT-PCR

Question 11

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?

Answer 11

The drug inhibits the specific thymine kinase receptor.

Question 12

In 1997, Dolly the sheep was cloned. Which of the following processes was used?

Answer 12

fusion of an adult cell’s nucleus with an enucleated sheep egg, followed by incubation in a surrogate

Question 13

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?

Answer 13

the nutrient broth only

Question 14

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.

Answer 14

III, II, IV, V, I

Question 15

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

Answer 15

post-transcriptional processing.

Question 16

Which was developed by a British researcher and causes DNA sequences to be transferred to a membrane and identified with a probe?

Answer 16

Southern blotting

Question 17

DNA microarrays have made a huge impact on genomic studies because they

Answer 17

allow the expression of many or even all of the genes in the genome to be compared at once.

Question 18

Which of the following techniques used to analyze gene function depends on the specificity of DNA base complementarity?

Answer 18

in vitro mutagenesis

Question 19

Which seals the sticky ends of restriction fragments to make recombinant DNA?

Answer 19

DNA ligase

Question 20

Which of the following separates molecules by movement due to size and electrical charge?

Answer 20

gel electrophoresis

Question 21

Which of the following is one of the technical reasons why gene therapy is problematic?

Answer 21

Transferred genes may not have appropriately controlled activity.

Question 22

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?

Answer 22

cDNA library

Question 23

Which of the following is used to make complementary DNA (cDNA) from RNA?

Answer 23

reverse transcriptase

Question 24

Gene therapy

Answer 24

had apparent success in treating disorders involving bone marrow cells.

Question 25

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

Answer 25

the ampicillin broth and the nutrient broth.

Question 26

Which of the following cuts DNA molecules at specific locations?

Answer 26

restriction enzymes

Question 27

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?

Answer 27

in situ hybriditation-FISH study to determine the chromosomal location of all chromosome 22 q fragments

Question 28

Plants are more readily manipulated by genetic engineering than are animals because

Answer 28

a somatic plant cell can often give rise to a complete plant.

Question 29

The DNA fragments making up a genomic library are generally contained in

Answer 29

recombinant plasmids of bacteria.

Question 30

Which describes the transfer of polypeptide sequences to a membrane to analyze gene expression?

Answer 30

Western blotting

Question 31

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?

Answer 31

engineered cells, when reintroduced into the patient, find their way back to the bone marrow.

Question 32

DNA technology has many medical applications. Which of the following is not done routinely at present?

Answer 32

introduction of genetically engineered genes into human gametes

Question 33

Genetic engineering is being used by the pharmaceutical industry. Which of the following is not currently one of the uses?

Answer 33

creation of products that will remove poisons from the human body

Question 34

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?

Answer 34

to decrease the production from a harmful gain-of-function mutated gene

Question 35

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

Answer 35

cut DNA again with RE Y and insert these fragments into the plasmid cut with the same enzyme.

Question 36

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

Answer 36

polymerase chain reaction (PCR)

Question 37

Which of the following is most closely identical to the formation of twins?

Answer 37

organismal cloning

Question 38

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?

Answer 38

to attach the DNA fragments to a permanent substrate

Question 39

Why are yeast cells frequently used as hosts for cloning?

Answer 39

they are eukaryotic cells

Question 40

Restriction fragments of DNA are typically separated from one another by which process?

Answer 40

gel electrophoresis

Question 41

What is the enzymatic function of restriction enzymes?

Answer 41

to cleave nucleic acids at specific sites

Question 42

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?

Answer 42

Cloning to produce embryonic stem cells may lead to great medical benefits for many.

Question 43

Scientists developed a set of guidelines to address the safety of DNA technology. Which of the following is one of the adopted safety measures?

Answer 43

Correct Microorganisms used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside of the laboratory.

Question 44

How does a bacterial cell protect its own DNA from restriction enzymes?

Answer 44

adding methyl groups to adenines and cytosines

Question 45

A student wishes to clone a sequence of DNA of ~200 kb. Which vector would be appropriate?

Answer 45

a BAC

Question 46

Which of the following would not be true of cDNA produced using human brain tissue as the starting material?

Answer 46

It could be used to create a complete genomic library.

Question 47

A principal problem with inserting an unmodified mammalian gene into a bacterial plasmid, and then getting that gene expressed in bacteria, is that

Answer 47

bacteria cannot remove eukaryotic introns.

Question 48

Which problems with animal cloning might result in premature death of the clones?

Answer 48

abnormal regulation due to variant methylation

Question 49

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?

Answer 49

recombination resulting in replacement of the wild type with the mutated gene

Question 50

Which of the following tools of recombinant DNA technology is incorrectly paired with its use?

Answer 50

DNA ligase-enzyme that cuts DNA, creating the sticky ends of restriction fragments

Question 51

In order to identify a specific restriction fragment using a probe, what must be done?

Answer 51

- 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

Question 52

Which of the following modifications is least likely to alter the rate at which a DNA fragment moves through a gel during electrophoresis?

Answer 52

altering the nucleotide sequence of the DNA fragment

Question 53

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?

Answer 53

a YAC with appropriate cellular enzymes

Question 54

As genetic technology makes testing for a wide variety of genotypes possible, which of the following is likely to be an increasingly troublesome issue?

Answer 54

the need to legislate for the protection of the privacy of genetic information

Question 55

Bacteria containing recombinant plasmids are often identified by which process?

Answer 55

exposing the bacteria to an antibiotic that kills cells lacking the resistant plasmid

Question 56

RFLP (Restriction fragment length polymorphism) analysis can be used to distinguish between alleles based on differences in which of the following?

Answer 56

restriction enzyme recognition sites between the alleles

Question 57

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?

Answer 57

prevention of transmission of plant allergens to the vaccine recipients

Question 58

Dideoxyribonucleotide chain-termination is a method of

Answer 58

sequencing DNA.

Question 59

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

Answer 59

in all four types of broth.

Question 60

Which of the following produces multiple identical copies of a gene for basic research or for large-scale production of a gene product?

Answer 60

gene cloning

Question 61

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?

Answer 61

The cells from the two sources exhibit different patterns of DNA methylation.

Question 62

A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using

Answer 62

reverse transcriptase to reconstruct the gene from its mRNA.

Question 63

Yeast artificial chromosomes contain which of the following elements?

Answer 63

centromere, telomeres, and an origin of replication

Question 64

The major advantage of using artificial chromosomes such as YACs and BACs for cloning genes is that

Answer 64

YACs and BACs can carry much larger DNA fragments than ordinary plasmids can.