Deck 23: Recombinant Dna Technology

Question 1

Results of research on the Human Genome Project should enable which of the following?

A) precise diagnosis of disease
B) individual risk assessment
C) prediction of the course of a disease
D) All of the above

Answer 1

All of the above

Question 2

Plasmids are usually introduced into bacterial cells by .

A) transfusion
B) transfection
C) transduction
D) transformation

Answer 2

transformation

Question 3

To be useful as a vector, restriction enzyme reaction sites should be placed

A) around antibiotic resistance genes.
B) within antibiotic resistance genes.
C) in the ori site.
D) inside TRP1 or URA3 genes.

Answer 3

within antibiotic resistance genes.

Question 4

Insert DNA may be produced by

A) the mechanical shearing of long DNA molecules.
B) digesting DNA with type II restriction endonucleases.
C) the action of reverse transcriptase on rRNA.
D) All of the above
E) Only A and B

Question 5

Which of the following is an advantage of phage vectors over plasmid vectors?

A) Recombinant DNA must be packaged into phage particles in vitro.
B) It is not possible to isolate a line of cells that can propagate the recombinant DNA molecule.
C) Transfection is more efficient than transformation for larger pieces of DNA.
D) All of the above

Question 6

DNA molecules which are constructed with DNA from different sources are called

A) exons.
B) introns.
C) transgenic DNA molecules.
D) recombinant DNA molecules.

Question 7

are small, circular double-stranded DNA molecules used as vectors for DNA fragments up to 20kb in size.

A) Exons
B) Plasmids
C) Introns
D) Cosmids

Question 8

is the propagation of individual host cells containing a recombinant DNA molecule.

A) Transformation
B) Cloning
C) Transduction
D) None of the above

Question 9

Which of the following is false?

A) Blunt end fragments of DNA can be ligated.
B) A sheared DNA fragment can be given sticky ends.
C) The enzyme deoxynucleotidyl transferase cannot generate sticky ends.
D) A synthetic DNA fragment, called a linker, can connect blunt end DNA fragments.

Question 10

General steps in the generation of a recombinant DNA molecule in the laboratory include

A) ligation of DNA segments.
B) cleavage of DNA into small fragments.
C) insertion of DNA fragments into a vector.
D) All of the above

Question 11

Bacterial artificial chromosomes BACs) require in order to successfully enter into bacterial cells.

A) transfection
B) electroporation
C) the use of complementary nucleotides
D) linkers

Question 12

Which of the following is true, concerning the plasmid vector, pBR322?

A) It contains an origin of replication ori).
B) It contains genes which confer resistance to the antibiotics ampicillin and tetracycline.
C) It contains a number of restriction sites that are useful for constructing RNA.
D) All of the above
E) Only A and B

Question 13

is the direct uptake of foreign DNA by a host cell.

A) Transfection
B) Transduction
C) Transformation
D) Conjugation

Question 14

Which of the following can function as a cloning vector?

A) plasmids
B) bacteriophages
C) viruses
D) All of the above
E) None of the above

Question 15

Properties of cloning vectors include each of the following, except

A) they may contain sequences which allow them to be replicated autonomously within a compatible host cell.
B) they may contain sequences which enable integration into the host genome.
C) only a select few of them may have a unique cloning site which can be cut by restriction endonucleases.
D) the most important vectors have restriction sites which are grouped together in a polylinker.

Question 16

Inserting DNA into a cloning site within the tet^R gene may cause the following

A) inactivation of the tet^R gene.
B) produce transformants which are sensitive to ampicillin.
C) produce transformants which are resistant to tetracycline.
D) All of the above

Question 17

In a blue/white screen

A) the blue colonies represent cells transformed with cloning vectors which contain inserts.
B) the white colonies represent cells transformed with recombinants.
C) the presence of blue dye identifies cells containing a disrupted a-galactosidase gene.
D) All of the above

Question 18

replicate in either prokaryotic or eukaryotic cells.

A) Phage vectors
B) Shuttle vectors
C) Cosmids
D) Transposons

Question 19

Which of the following list gives the amount of foreign DNA that can be inserted into vectors is not true?

A) YAC - 400 to 500 kb
B) Plasmids - 20 kb
C) Bacteriophage l - up to 22 kb
D) Cosmids - up to 5 kb

Question 20

Which of the following statements is true concerning sticky ends?

A) They are fragments with single strand extensions at only the 5ʹ end of a restriction endonuclease.
B) They can transiently base pair to complementary sticky ends on vector DNA.
C) They can covalently join to the vector in a reaction catalyzed by DNA gyrase.
D) All of the above

Question 21

Which of the following is true concerning genomic libraries?

A) Genomic libraries often use cloning vectors derived from plasmid vectors.
B) Total restriction digestion frequently is used to ensure that the library contains every gene.
C) Genomic libraries include both expressed and non-expressed DNA from an organism.
D) All of the above

Question 22

A molecule that specifically recognizes the desired piece of DNA in a large library is known as a

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

Question 23

The construction of a cDNA library is completed by

A) purifying mRNA molecules from eukaryotes.
B) ligating the cDNA molecules to vectors and introducing the recombinants into host cells.
C) incubating the mRNA population with oligodeoxythymidylate.
D) adding synthetic oligonucleotides to sticky-ended cDNA molecules.

Question 24

Under normal conditions, about what minimum range of sequence similarity is desired to obtain hybridization between a cDNA probe and the desired gene in a library?

A) 5% to 10%
B) 30% to 40%
C) 60% to 70%
D) 90% to 95%

Question 25

is a technique used to link noncontiguous recombinants from the same gene or to identify genes whose sequence and gene product are unknown other than by the effects of mutation.

A) Transformation
B) Polymerase chain reaction
C) Antibody screening
D) Chromosome walking

Question 26

Mechanical shearing is often the preferred method of fragmenting genomic DNA when constructing a genomic DNA library. Why would this method be preferred over complete digestion with restriction enzymes?

A) Enzymes might produce fragments that are too small or too large to be cloned.
B) Enzyme cleavage can interrupt important gene sequences, in which case not all genes may be represented in the library.
C) Shearing ensures the library contains overlapping fragments of DNA, which makes it possible to perform a chromosome walk.
D) All of the above

Question 27

Which formula may be implemented to determine the probability P) that a library of a given size contains a particular clone? N is the number of recombinant clones in the library; n is the frequency of occurrence of a desired clone)

A) P = 1 + 1 - N)ⁿ
B) P = 1 - 1 - N)ⁿ
C) P = 1 - 1 - n)^N D) P = 1 + 1 - n)^N

Question 28

A/an is often used to enable bacteria to produce large amounts of eukaryotic protein.

A) cosmid
B) transgenic phage
C) expression vector
D) cDNA clone

Question 29

Which isare) appropriate for use as a labeled probes) to screen a DNA library?

A) cloned cDNA
B) antibodies
C) mRNA
D) All of the above

Question 30

Which is not necessary as part of an expression vector used in E. coli?

A) marker gene
B) ribosome binding site
C) Taq polymerase gene
D) strong promoter sequence

Question 31

The human genome contains about bp of DNA.

A) 3.2 thousand
B) 3.2 million
C) 3.2 billion
D) 3.2 trillion

Question 32

In a cDNA library the probability of finding the desired clone depends on .

A) the abundance of the original mRNA
B) the genome size
C) the average length of mRNA
D) All of the above

Question 33

In a genomic DNA library the frequency of occurrence of a desired clone, n, also represents

A) the number of recombinant clones in the library.
B) the abundance of the relevant mRNA molecule.
C) the ratio of the size of the insert to the size of the genome.
D) the probability that a library of a given size contains a particular clone.

Question 34

What is the frequency of occurrence of a desired clone from a YAC library of genomic DNA if the insert size is 400 kbp and the genome contains 2 × 10⁶ kbp?

A) 2 × 10^-4
B) 8 × 10⁸
C) 5 × 10³
D) 1.25 × 10^-9

Question 35

To discover whether a species has a gene that is similar but not identical to the cDNA of another species, one can

A) prepare proteins from one species only.
B) isolate the two different genes first.
C) hybridize using histone.
D) alter the temperature and salt concentrations used in the hybridization.

Question 36

Which is true about the frequency of occurrence of a desired clone from a genomic DNA library?

A) It depends on the abundance of the associated mRNA.
B) It is directly proportional to the size of the genome.
C) It is found as a ratio of the size of the insert to the size of the genome.
D) It cannot be calculated. It is totally random.

Question 37

Which of the following may function as a labeled probe?

A) oligonucleotides
B) antibodies
C) radioactive isotopes
D) fluorescent dyes
E) All of the above

Question 38

How many recombinant clones must be screened in order to be 99% certain that a particular gene is found in a YAC library of human DNA where the average size of an insert is 500 kbp? The human genome size is about 3.2 × 10⁶ kbp.

A) 6000
B) 30,000
C) 1,000,000
D) 30,000,000

Question 39

cDNA libraries from liver cells are different than cDNA libraries from kidney cells because

A) the DNA is not the same in the two types of cells.
B) reverse transcriptase acts differently in the two types of cells.
C) mRNA is different in the two types of cells.
D) polyA is present at 3ʹ ends of mRNA in one cell type only.

Question 40

How many recombinant clones must be present in a cDNA library to be 95% certain that the library contains one clone of a particular mRNA molecule representing 0.005% of the total mRNA?

A) 5.9 × 10³
B) 6 × 10⁴
C) 6 × 10⁶
D) 5 × 10⁵

Question 41

Who won the Nobel Prize in 1993 for his work on site-directed mutagenesis?

A) Kary Mullis
B) Michael Smith
C) Herbert Boyer
D) James Watson

Question 42

was the first bacterial genome sequence to be published.

A) Haemophilus influenzae
B) E. coli
C) Agrobacterium tumefaciens
D) S. cerevisiae

Question 43

Which is not an important feature of site-directed mutagenesis of cloned DNA?

A) It can be used to introduce point mutations.
B) It is faster than the complete in vitro synthesis of mutant genes.
C) It can be used to exponentially amplify the amount of DNA in a sample.
D) It allows for easy screening of transformants by using labeled oligonucleotides.

Question 44

Restriction fragment length polymorphisms are the result of .

A) mutation
B) chromosome deletions
C) chromosome recombination
D) all of the above

Question 45

What is the purpose of the heating cycle during PCR?

A) activates Taq polymerase
B) denatures the DNA
C) facilitates the attachment of RNA primers
D) increases the rate of polymerization by increasing the rate of diffusion of free nucleotides

Question 46

Plasmids replicate autonomously within a host.

Question 47

Restriction fragment length polymorphisms refer to .

A) variations in the size of mature mRNA transcripts from one individual to the next
B) variations in the lengths of genomic DNA fragments from a single individual from samples that are treated with different endonucleases
C) variations in the lengths of genomic DNA fragments among DNA from different tissues in a single individual that are treated with the same endonuclease
D) variations in the lengths of genomic DNA fragments among individuals that are treated with the same endonuclease

Question 48

It can be difficult for bacteria to produce functional eukaryotic proteins even when all the components necessary for gene expression are present because .

A) eukaryotes do not use the Shine-Dalgarno sequence
B) many eukaryotic proteins must be post-translationally modified
C) of the size difference between eukaryotic and prokaryotic ribosomes
D) of differences in the prokaryotic and eukaryotic genetic codes

Question 49

Why is Taq polymerase used in PCR rather than DNA polymerases from other sources?

A) It is heat stable.
B) It is faster than most other DNA polymerases.
C) It is cheaper and easier to isolate than other DNA polymerases.
D) All of the above

Question 50

After ten cycles of PCR, by approximately what factor will the number of DNA molecules in a sample be increased? Assume maximum efficiency.

A) 10
B) 20
C) 1000
D) 10,000,000,000

Question 51

A mouse embryo is transformed with recombinant DNA from a rat. The resulting mouse is a organism.

A) mosaic
B) composite
C) transgenic
D) sterile

Question 52

Restriction enzymes randomly cleave DNA.

Question 53

Which of the following is not an application of PCR?

A) formation of proteins from RNA fragments
B) investigation of molecular evolution
C) amplification of genes in paternity testing
D) construction of phylogenetic trees
E) detection of microoranisms from clinical specimens blood, urine, etc.)

Question 54

The Ti plasmid is derived from .

A) the bacterium E. coli
B) a soil bacterium, Agrobacterium tumefaciens
C) yeast, S. cerevisiae
D) the tobacco plant

Question 55

How might infection of a plant by E. coli transformed with a recombinant Ti plasmid be used to have a new gene e.g. insect toxin) expressed in all cells of the plant?

A) The original plant will eventually express the new gene in all its cells even if only a few cells of the plant are initially infected by E. coli.
B) Pollen cells must be infected and then used to produce the next generation of plants which will express the new gene in all cells.
C) Any cell from the original plant that is infected with the E. coli is removed and treated to dedifferentiate and eventually to grow into an entire new plant in which the new gene is expressed throughout.
D) All of the above

Question 56

Shine-Dalgarno sequences are components of plasmid vectors which help to maximize the expression of inserted genes.

Question 57

Yeast artificial chromosomes YACs are introduced into yeast cells as circular molecules.

Question 58

Which component is not necessary for a PCR experiment?

A) free nucleotides
B) reverse transcriptase
C) RNA primers
D) DNA polymerase
E) template DNA

Question 59

Reverse transcriptase is a vital enzyme in the development of a genomic DNA library.

Question 60

It is possible to clone a gene for a protein that is not expressed in the tissue from which the cDNA library was derived.

Question 61

For genes that are highly conserved, probes developed from one species can be used to screen clones from many other species.

Question 62

It is possible for eukaryotic genes with introns to be isolated from genomic libraries and expressed directly in yeast cells.

Question 63

Complementary DNA cDNA is single-stranded DNA made with reverse transcriptase.

Question 64

Cloned cDNA is used less frequently than mRNA as a probe for protein encoding genes in genomic DNA libraries.

Question 65

Changing factors such as the salt concentration and temperature can be used to vary the stringency of hybridization and allow for more or less mismatches in base pairing.

Question 66

RFLP analysis is a very useful technique for genetic analysis and forensic studies, but it is not precise enough to distinguish genetic differences between highly related individuals such as siblings or parents and children.

Question 67

The oligodeoxythymidylate oligo dT fragment functions as a primer for synthesis of a complementary DNA strand by reverse transcriptase.

Question 68

RFLPs are very useful in determining paternity.

Question 69

Exons and introns are equally represented in a cDNA library.

Question 70

Chromosome walking involves the isolation and sequencing of consecutive segments of DNA isolated after treatment with a restriction endonuclease.

Question 71

In general, when constructing a YAC library of genomic DNA the smaller the insert used the fewer clones are needed.

Question 72

An individual is treated for cystic fibrosis by a recombinant virus administered through an inhaler so the virus can ʺinfectʺ the cells lining the lungs. In the lungs, the recombinant DNA is incorporated into the patientʹs genomic DNA and produces a protein product that helps relieve the symptoms of the disease. Children born to this patient after the treatment can be expected to also carry the recombinant genes and benefit from them if they too suffer from cystic fibrosis.

Question 73

Insulin and growth hormones are two examples of proteins that can be produced in great quantities by their synthesis in bacteria.