19&20

Emerging viruses arise by

A) mutation of existing viruses. B) the spread of existing viruses to new host species. C) the spread of existing viruses more widely within their host species. ANSWER : ALL OF THEM!!!

How does a genomic library differ from a cDNA library?

A genomic 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.

A linear piece of viral DNA of 8 kb can be cut with either of two restriction enzymes (X and Y). These are subjected to electrophoresis and produce the following bands:

B

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.

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

DNA ligase

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

What is the function of reverse transcriptase in retroviruses?

It uses viral RNA as a template for DNA synthesis.

The first cell whose entire genome was sequenced was which of the following?

H. influenzae in 1995

Which uses reverse transcriptase to make cDNA followed by amplification?

RT-PCR

Why do RNA viruses appear to have higher rates of mutation?

Replication of their genomes does not involve the proofreading steps of DNA replication.

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 researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?

The plants would develop the typical symptoms of TMV infection.

Which of the following represents a difference between viruses and viroids?

Viruses have capsids composed of protein, whereas viroids have no capsids.

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

Western blotting

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.

Which of the following describes plant virus infections?

They are spread throughout a plant by passing through the plasmodesmata.

Why are viruses referred to as obligate parasites?

They cannot reproduce outside of a host cell.

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

Transferred genes may not have appropriately controlled activity.

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.

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

In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host genes. Therefore, which of the following would you expect of the genes of the bacteriophage?

control of more than one gene in an operon

In recombinant DNA methods, the term vector can refer to

a plasmid used to transfer DNA into a living cell.

Which enzyme was used to produce the molecule in Figure 20.1?

a restriction enzyme

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.

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

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

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

adding methyl groups to adenines and cytosines

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.

Viral envelopes can best be analyzed with which of the following techniques?

antibodies against specific proteins not found in the host membranes

RNA viruses require their own supply of certain enzymes because

host cells lack enzymes that can replicate the viral genome.

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

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

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

gel electrophoresis

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

gel electrophoresis

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

Which of the following characteristics, structures, or processes is common to both bacteria and viruses?

genetic material composed of nucleic acid

Which of the following can be effective in preventing viral infection in humans?

getting vaccinated

Which of the following molecules make up the viral envelope?

glycoproteins

Gene therapy

had apparent success in treating disorders involving bone marrow cells.

Genetically engineered plants

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

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

introduction of genetically engineered genes into human gametes

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

organismal cloning

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)

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.

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

Which of the following terms describes bacteriophage DNA that has become integrated into the host cell chromosome?

prophages

Most human-infecting viruses are maintained in the human population only. However, a zoonosis is a disease that is transmitted from other vertebrates to humans, at least sporadically, without requiring viral mutation. Which of the following is the best example of a zoonosis?

rabies

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

recombinant plasmids of bacteria.

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

Given Baltimoreʹs scheme,a positive sense single-stranded RNA virus such as the polio virus would be most closely related to which of the following?

retroviruses that require a DNA intermediate

Dideoxyribonucleotide chain-termination is a method of

sequencing DNA.

What characteristics of electron microscopes make them most useful for studying viruses?

shorter wavelengths providing higher resolution

Viral genomes vary greatly in size and may include from four genes to several hundred genes. Which of the following viral features is most apt to correlate with the size of the genome?

size and shape of the capsid

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 that do not take up any plasmids would grow on which media?

the nutrient broth only

The host range of a virus is determined by

the proteins on its surface and that of the host.

DNA fragments from a gel are transferred to a nitrocellulose paper during the procedure called Southern blotting. What is the purpose of transferring the DNA from a gel to a nitrocellulose paper?

to attach the DNA fragments to a permanent substrate

What is the enzymatic function of restriction enzymes?

to cleave nucleic acids at specific sites

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

Which of the following best describes the complete sequence of steps occurring during every cycle of PCR?

2, 1, 4

Based on the above table, which virus meets the requirements for a bacteriophage?

A

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?

A cDNA library, made using mRNA from human lens cells, which would be expected to contain many copies of crystallin mRNAs

Which of the following is characteristic of the lytic cycle?

A large number of phages is released at a time.

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

A, B, and C are correct.

Which of the following series best reflects what we know about how the flu virus moves between species?

An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates and is passed to a new species such as a bird, the virus mutates and can be transmitted to humans.

The segment of DNA shown in Figure 20.2 has restriction sites I and II, which create restriction fragments A, B, and C. Which of the gels produced by electrophoresis shown below best represents the separation and identity of these fragments?

B

Which of the following procedures would produce RFLPs?

C

Which of the following are probably siblings?

C and D

Which of the following statements is consistent with the results?

C is the child of A and B.

Based on the above table, which virus meets the Baltimore requirements for a retrovirus?

D

Which of the following statements is most likely true?

D is the child of A and B.

Which of the following would be a reasonably efficient technique for confirming the diagnosis of CML?

FISH study to determine the chromosomal location of all chromosome 22 q fragments

Which of the following sequences in double-stranded DNA is most likely to be recognized as a cutting site for a restriction enzyme?

GGCC CCGG

Which treatment could definitively determine whether or not the component is a viroid?

I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious

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. ExtractplasmidDNAfrombacterialcells. 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

If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities

III. culturingthesubstancebyitselfonnutritivemedium,away from any plant cells

Which treatment would you use to determine if the agent is a prion?

IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious

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.

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

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

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

Southern blotting

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have

T4 protein and T4 DNA.

Why would Gleevec most probably cause remission of the disease?

The drug inhibits the specific thymine kinase receptor.

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?

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

Which of the following is the most probable fate of a newly emerging virus that causes high mortality in its host?

The newly emerging virus will die out rather quickly or will mutate to be far less lethal.

Which of the following statements describes the lysogenic cycle of lambda (λ) phage?

The phage genome replicates along with the host genome.

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.

Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?

Viral genomes are usually more similar to the genome of the host cell than to the genomes of viruses that infect other cell types.

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

a BAC

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

Which of the following is the best predictor of how much damage a virus causes?

ability of the infected cell to undergo normal cell division

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

abnormal regulation due to variant methylation

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

To cause a human pandemic, the H5N1 avian flu virus would have to

become capable of human-to-human transmission.

Yeast artificial chromosomes contain which of the following elements?

centromere, telomeres, and an origin of replication

Which of the following accounts for someone who has had a herpesvirus-mediated cold sore or genital sore getting flare-ups for the rest of life?

copies of the herpesvirus genome permanently maintained in host nuclei

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

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

Bacteria containing recombinant plasmids are often identified by which process?

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

Bacteria that contain the plasmid, but not the eukaryotic gene, would grow

in all four types of broth.

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

in vitro mutagenesis

Antiviral drugs that have become useful are usually associated with which of the following properties?

interference with the viral reproduction

What are prions?

misfolded versions of normal brain protein

RFLP analysis can be used to distinguish between alleles based on differences in which of the following?

restriction enzyme recognition sites between the alleles

Which of the following cuts DNA molecules at specific locations?

restriction enzymes

What is the name given to viruses that are single-stranded RNA that acts as a template for DNA synthesis?

retroviruses

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

reverse transcriptase

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.

Bacteria containing a plasmid into which the eukaryotic gene has integrated would grow in

the ampicillin broth and the nutrient broth.

Why are yeast cells frequently used as hosts for cloning?

they are eukaryotic cells

The difference between vertical and horizontal transmission of plant viruses is that

vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant.