Chapter 9 Quiz

In order to get around the lack of ability of prokaryotes to remove introns from precursor RNA, it may be necessary to: use different promoters. use the DNA after it has been processed. generate cDNA from mRNA. turn cDNA into mRNA. use the DNA directly.

generate cDNA from mRNA.

The Ti plasmid is used as a vector to transfer DNA into plant cells. bacteria. viruses. protozoa. animal cells.

plant cells.

Most eukaryotic genes are cloned directly into the vector for expression in prokaryotes. True False

False

Identify the correct sequence in which the steps below occur during a single PCR cycle. 1. Complementary base pairing between primers and target DNA. 2. Addition of DNA nucleotides by Taq DNA polymerase. 3. Heat separation of strands of target DNA. 3; 1; 2 1; 2; 3 2; 1; 3 2; 3; 1 1; 3; 2

3; 1; 2

Starting with a single piece of dsDNA, after 3 PCR cycles there are: 2 additional pieces of dsDNA. 4 additional pieces of dsDNA. 1 additional piece of dsDNA. 8 additional pieces of dsDNA. 16 additional pieces of dsDNA.

8 additional pieces of dsDNA

Scientists have cloned the human insulin gene into E. coli. Which of the following would NOT have been used in the procedure? Competent bacteria A bacteriophage A restriction enzyme A plasmid DNA ligase

A bacteriophage

Which of the following is NOT true about an ideal vector? A vector contains a selectable marker. A vector may be a plasmid or bacteriophage. A vector contains an origin of replication. A vector has a restriction enzyme recognition site. A vector contains an RNA primer.

A vector contains an RNA primer.

Which nitrogenous base does the dideoxynucleotide ddNTP contain? Cytosine Adenine A, T, G or C Guanine Thymine

A, T, G or C

The Ti plasmid is naturally found in: Staphylococcus. Escherichia. E. coli AND Staphylococcus. Pseudomonas. Agrobacterium.

Agrobacterium.

Plasmids work well for insertion of foreign DNA into a cell. Which statement is FALSE? Plasmids can replicate independent of the chromosome. Plasmids have an origin of replication. All known bacteria contain plasmids of some kind. Plasmids are relatively small compared with a chromosome. Plasmids usually contain a selectable marker such as antibiotic resistance.

All known bacteria contain plasmids of some kind.

Genetic engineering of plants has so far produced: All of the answer choices are correct. plants with increased nutritional value. pest-resistant plants. plants that are herbicide resistant. None of the answer choices is correct.

All of the answer choices are correct.

PCR is particularly useful in: relatively quickly producing results. detecting viable yet non-culturable organisms. dealing with very small numbers of bacteria. assessing impure (multiple types of bacteria present) samples. All of the answer choices are correct.

All of the answer choices are correct.

During PCR, which primer anneals to template DNA at its 3' end? Primers don't bind to template DNA. Both the forward primer and the reverse primer. The forward primer only. Either the forward primer or the reverse primer. The reverse primer only.

Both the forward primer and the reverse primer.

The polymerase chain reaction is used to duplicate small sections of: RNA. DNA. lipids. lipopolysaccharides. proteins.

DNA

Sexually transmitted human papillomavirus (HPV) strains are among the most common of the sexually transmitted infection (STI) agents. Some HPV strains (low risk) cause papillomas—warty growths of the external and internal genitalia. Other strains (high risk) cause lesions of mucosal surfaces and are more problematic—approximately 15 of these strains are strongly associated with cancer of the cervix, penis, rectum, vagina, or throat. These high-risk strains include HPVs 16, 18, 31, and 45. You have been asked to give a short presentation on HPV and its detection by PCR (the HPV test). Following your presentation, you answer questions from your audience. HPV is a non-enveloped, double stranded DNA virus. What are the components of this virus? DNA, RNA, and protein RNA, protein, and phospholipids RNA and protein DNA, protein, and phospholipids DNA and protein

DNA and protein

The molecule(s) that act as molecular glue to bind DNA fragments together is/are: DNA ligase. polymerase. DNAse AND ligandase. ligandase. DNAse.

DNA ligase.

Why are primers needed in DNA sequencing? DNA polymerase needs a primer to help it recognize a vector for gene insertion. DNA polymerase needs a primer for proofreading and mismatch repair after a gene has been sequenced. DNA polymerase needs a primer because it can only add nucleotides to an existing nucleotide strand. All of the answer choices are correct. The primer acts as a template for the dideoxynucleotides and deoxynucleotides.

DNA polymerase needs a primer because it can only add nucleotides to an existing nucleotide strand.

Possessing the entire sequence of a particular human genome may not be as useful as we think. Why not? Due to the presence of introns/exons, and splicing of RNA after transcription, the DNA sequence doesn't necessarily tell us the exact number/type of proteins that will eventually be made from it. It's not the DNA sequence that matters—we need to know the mRNA sequence of the human genome. Due to the presence of introns/exons, and pre-transcriptional modification, the protein profile varies considerably among people, so it would be better to determine that. Every human genome is different enough that knowing ONE human's DNA sequence can't tell us almost anything about ALL humans. The amount of "junk DNA" present in the human genome masks any useful genetic information that we'd like to obtain.

Due to the presence of introns/exons, and splicing of RNA after transcription, the DNA sequence doesn't necessarily tell us the exact number/type of proteins that will eventually be made from it.

Which of the following is NOT true about laboratory strains of E. coli being desirable hosts for genetic engineering? All of the answer choices are correct. The genetics of E. coli is very well known. E. coli is fastidious but can usually be grown in the lab. E. coli has known phenotypic characteristics. E. coli is especially able to express foreign genes.

E. coli is fastidious but can usually be grown in the lab.

The gene for human insulin has been successfully cloned in: pig cells. human cells. E. coli. S. aureus. rhinovirus.

E. coli.

Bacteria use CRISPR for gene editing. True False

False

Sexually transmitted human papillomavirus (HPV) strains are among the most common of the sexually transmitted infection (STI) agents. Some HPV strains (low risk) cause papillomas—warty growths of the external and internal genitalia. Other strains (high risk) cause lesions of mucosal surfaces and are more problematic—approximately 15 of these strains are strongly associated with cancer of the cervix, penis, rectum, vagina, or throat. These high-risk strains include HPVs 16, 18, 31, and 45. You have been asked to give a short presentation on HPV and its detection by PCR (the HPV test). Following your presentation, you answer questions from your audience. Which is the CORRECT definition of PCR? Procedure in which a fragment of DNA is inserted into a vector and then transferred into another cell, where it then replicates. The process in which two complementary strands of DNA from different sources are annealed to create a hybrid double-stranded molecule. Use of the enzyme reverse transcriptase to generate cDNA from mRNA, and then amplifying the cDNA exponentially using RNA polymerase. In vitro technique used to repeatedly duplicate (amplify) a specific region of a DNA molecule, increasing the number of copies exponentially. In vitro process of determining the nucleotide sequence of a DNA molecule using a variety of enzymes.

In vitro technique used to repeatedly duplicate (amplify) a specific region of a DNA molecule, increasing the number of copies exponentially.

Why must an agarose gel be placed in a buffer solution for DNA gel electrophoresis? Even distilled, autoclaved water has a high number of DNases in it that would destroy the DNA. The DNA fragments will disintegrate unless there is a buffer present to prevent this from happening. The buffer contains phosphates, and the DNA fragments must be phosphorylated before they move in agarose. Ions in the buffer conduct the electric current needed to move the DNA fragments in the gel matrix.

Ions in the buffer conduct the electric current needed to move the DNA fragments in the gel matrix.

Polymerase chain reaction (PCR) can be used to perform DNA sequencing reactions. In this case, are two primers (a forward and a reverse) necessary? Yes—and it will be important to make sure that the primer pairs are made with dideoxynucleotides that are labeled with fluorescent dyes. Otherwise, you won't be able to detect the fragments that are made in the PCR process. Yes—if you only have one primer, you will only be able to determine the dideoxynucleotide sequence of RNA, which is a single-stranded molecule. Yes—you can't perform PCR without two specific primers to amplify the region in question in the DNA. No—dideoxynucleotide sequencing depends on different length fragments being formed and then separated based on size. This can take place with only a specific forward OR a specific reverse primer. No—you actually need a primer pair for each round of DNA amplification ... so you'll need many, many primer pairs, depending how many rounds you plan to do.

No—dideoxynucleotide sequencing depends on different length fragments being formed and then separated based on size. This can take place with only a specific forward OR a specific reverse primer.

The sequence of cDNA synthesized from an mRNA template with the sequence AUGGUA would be ________. This cDNA probe would hybridize to gene chip DNA with the sequence ________. TACCAT; ATGGTA TACCAT; AUGGUA AUGGUA; TACCAT UACCAU; ATGGTA AUGGUA; AUGGUA

TACCAT; ATGGTA

Tuberculosis (TB) is caused by the acid-fast bacterium Mycobacterium tuberculosis. Although most TB cases affect the lungs (pulmonary TB), some infections occur in other body sites (extrapulmonary TB). Among these cases, lymph node tuberculosis (LNTB) is the most common. Diagnosis of LNTB by conventional methods (staining, biochemical tests) has limitations—for example, formaldehyde preservation of tissue biopsies interferes with the acid-fast stain, leading to underdiagnosis or misdiagnosis. Now fluorescent in situ hybridization (FISH) is being used to diagnose extrapulmonary TB. In a recent research article describing the use of FISH to detect LNTB, the authors noted that they used probes that were only 20 base pairs (bp) in length rather than the conventional 100 bp—500 bp. Given what you know about acid-fast bacteria, why do you think they took this approach? Mycobacteria have a lipopolysaccharide outer membrane through which larger probes cannot enter. The nature of the Mycobacterial capsule likely makes is difficult for larger probes to enter the cell. The nature of the Mycobacterial cell wall likely makes is difficult for larger probes to enter the cell. Mycobacteria have smaller ribosomes than any other bacteria and the probes are targeted at rRNA. The nature of the Mycobacterial cytoplasmic membrane likely makes is difficult for larger probes to enter the cell.

The nature of the Mycobacterial cell wall likely makes is difficult for larger probes to enter the cell.

Sexually transmitted human papillomavirus (HPV) strains are among the most common of the sexually transmitted infection (STI) agents. Some HPV strains (low risk) cause papillomas—warty growths of the external and internal genitalia. Other strains (high risk) cause lesions of mucosal surfaces and are more problematic—approximately 15 of these strains are strongly associated with cancer of the cervix, penis, rectum, vagina, or throat. These high-risk strains include HPVs 16, 18, 31, and 45. You have been asked to give a short presentation on HPV and its detection by PCR (the HPV test). Following your presentation, you answer questions from your audience. PCR generates a DNA fragment of a distinct size even when the whole viral chromosome is used as a template. What determines the boundaries of the amplified fragment? The position of a termination sequence, which causes the Taq polymerase to fall off the template. The temperature at which the elongation step in each cycle is carried out. The concentration of one particular deoxynucleotide in the reaction. The sites on the template DNA to which the specific primers used in the reaction anneal. The length of time of the elongation step in each cycle.

The sites on the template DNA to which the specific primers used in the reaction anneal.

A DNA microarray contains oligonucleotides that contain a label. True False

True

A very common vector is a plasmid. True False

True

Agarose gel electrophoresis may be considered as a partial purification technique. True False

True

It is useful to have a reference sequence when assembling DNA sequence data in high through-put methods because assembly will be quicker if two sequences can be compared. True False

True

PCR is useful for amplifying a particular section of DNA. True False

True

Tuberculosis (TB) is caused by the acid-fast bacterium Mycobacterium tuberculosis. Although most TB cases affect the lungs (pulmonary TB), some infections occur in other body sites (extrapulmonary TB). Among these cases, lymph node tuberculosis (LNTB) is the most common. Diagnosis of LNTB by conventional methods (staining, biochemical tests) has limitations—for example, formaldehyde preservation of tissue biopsies interferes with the acid-fast stain, leading to underdiagnosis or misdiagnosis. Now fluorescent in situ hybridization (FISH) is being used to diagnose extrapulmonary TB. How are target cells identified using the FISH technique? Using a fluorescence microscope. Using DNA sequencing. Using DNA microarrays. Using an electron microscope. By detecting UV levels.

Using a fluorescence microscope.

When a vector that uses the lacZ gene as a second marker is used in a cloning experiment, bacteria that contain the recombinant DNA will give rise to Blue colonies White colonies

White colonies

Sexually transmitted human papillomavirus (HPV) strains are among the most common of the sexually transmitted infection (STI) agents. Some HPV strains (low risk) cause papillomas—warty growths of the external and internal genitalia. Other strains (high risk) cause lesions of mucosal surfaces and are more problematic—approximately 15 of these strains are strongly associated with cancer of the cervix, penis, rectum, vagina, or throat. These high-risk strains include HPVs 16, 18, 31, and 45. You have been asked to give a short presentation on HPV and its detection by PCR (the HPV test). Following your presentation, you answer questions from your audience. HPV is a DNA virus and can be detected in a sample using PCR. Is it possible to detect an RNA virus using this technique or something similar? No; there is no known process by which RNA can be copied because the subunits of RNA are amino acids and these cannot be amplified without the use of ribosomes. Yes; a variation of PCR is RT-PCR in which an enzyme called reverse transcriptase generates cDNA from mRNA in a sample, and that cDNA is then amplified exponentially. There is no answer to this question because nobody has ever tried to amplify RNA; viruses contain both DNA and RNA so it is always possible to detect the DNA component. Yes; Taq polymerase is a unique DNA polymerase that can copy either RNA or DNA, so it doesn't matter what type of virus is present—the enzyme will still detect it in a PCR reaction. No; PCR can only be carried out on a double-stranded molecule such as DNA, and RNA is a single-stranded molecule.

Yes; a variation of PCR is RT-PCR in which an enzyme called reverse transcriptase generates cDNA from mRNA in a sample, and that cDNA is then amplified exponentially.

In a FISH experiment, what would happen if unbound probe was not washed off? Nothing—the target nucleotide sequences are labeled, not the probe. Therefore, excess unbound probe wouldn't matter for the experiment. You would get false-positive results in different areas where the probe hadn't actually bound, but it was still sitting there and lighting up. Your FISH would be floating at the top of the tank due to the toxicity of the probe building up within them. Nothing—it's not necessary to wash off the unbound probe and doing so just adds an extra step to the procedure. You would get an intermediate color on the array because of the presence of both bound and unbound probes that fluoresce at different temperatures.

You would get false-positive results in different areas where the probe hadn't actually bound, but it was still sitting there and lighting up.

Taq polymerase is: an RNA polymerase AND an enzyme from Escherichia coli. a reverse transcriptase. an RNA polymerase. a heat-stable DNA polymerase from Thermus aquaticus. an enzyme from Escherichia coli.

a heat-stable DNA polymerase from Thermus aquaticus.

Goal(s) of gene cloning may be to produce: more copies of the host cell. many copies of the gene for sequencing. a protein, many copies of the gene to be used as a probe, AND many copies of the gene for sequencing. a protein. many copies of the gene to be used as a probe.

a protein, many copies of the gene to be used as a probe, AND many copies of the gene for sequencing.

The polymerase chain reaction is used to: produce long polymers of amino acids to be used in electrophoresis. amplify mRNA. produce proteins. amplify certain sections of DNA. produce long polymers of carbohydrates to be used in electrophoresis.

amplify certain sections of DNA.

Short tandem repeats (STRs): are important sites in vectors where foreign DNA can be integrated. are useful in identifying specific individuals. are generally found in exons. are DNA fragments generated during PCR. are errors that can arise during DNA sequencing.

are useful in identifying specific individuals.

All of the following are true about DNA probes EXCEPT they: may be obtained from similar genes from another organism. are usually tagged dsRNA. may be obtained from denatured tagged dsDNA. may be synthesized usually using information based on the protein sequence. may be tagged with a fluorescent dye.

are usually tagged dsRNA.

The energy to separate fragments during agarose gel electrophoresis is supplied by: agarosis. buffers. electricity. gravity. active transport.

electricity.

Human DNA cut with restriction enzyme A can be joined to: uncut human DNA. bacterial DNA cut with restriction enzyme H. bacterial DNA cut with restriction enzyme A. bacterial DNA cut with a human restriction enzyme. uncut bacterial DNA.

bacterial DNA cut with restriction enzyme A.

Mitochondrial DNA (mtDNA) in humans: is always donated to the offspring from both parents. is linear, single-stranded DNA. can be used to identify related people. can be isolated only from intact embryos. can be used to establish paternity.

can be used to identify related people.

A dye often used for its ease and sensitivity to visualize nucleic acid after agarose gel electrophoresis is: crystal violet. gold oxide. ethidium bromide. nigrosin. malachite green.

ethidium bromide.

Double-stranded DNA will separate into two strands when exposed to: low salt AND low pH high pH AND low salt low temperature AND high salt high temperature AND low pH high temperature AND high pH.

high temperature AND high pH.

Knowing the sequence of a genome is useful in: identifying genetic alterations associated with disease, studying evolutionary relationships, AND determining protein sequences. determining protein sequences BUT not identifying genetic changes. determining protein sequences AND identifying genetic alterations associated with disease. studying evolutionary relationships AND determining protein sequences. identifying genetic alterations associated with disease AND studying evolutionary relationships.

identifying genetic alterations associated with disease, studying evolutionary relationships, AND determining protein sequences.

Selecting for transformants involves: identifying organisms that are producing DNA. identifying organisms that have taken up recombinant DNA. identifying organisms that are producing antibiotics. identifying organisms that are producing proteins. identifying organisms that have taken up recombinant RNA.

identifying organisms that have taken up recombinant DNA.

DNA molecules that contain pieces of DNA from two different sources are defined as: mutation. genetic engineering. gene cloning. recombinant DNA. biotechnology.

recombinant DNA.

DNA molecules that contain pieces of DNA from two different sources are defined as: recombinant DNA. biotechnology. mutation. gene cloning. genetic engineering.

recombinant DNA.

The size of the amplified DNA fragment generated during PCR is determined by: the location to which the primers anneal. how much Taq polymerase is used. the size of the template DNA. the time for each cycle. how many cycles are performed.

the location to which the primers anneal.

A danger in using E. coli in cloning is that: E. coli could cause disease. the human cells may reject the insertion. working with E. coli requires a BSL3 laboratory. the exons may invert the introns. the outer membrane is toxic to humans.

the outer membrane is toxic to humans.

Restriction enzymes have proved so useful in manipulating DNA because: they cut at defined sites AND the sticky ends make it very easy to allow recombination of DNA with RNA. they cut at random sites AND the sticky ends make it very easy to allow recombination of any type of DNA. they protect eukaryotes against virus attack AND they cut both RNA and DNA. they cut at defined sites AND the sticky ends make it very easy to allow recombination of any type of DNA. they protect eukaryotes against virus attack AND the sticky ends make it very easy to allow recombination of DNA with RNA.

they cut at defined sites AND the sticky ends make it very easy to allow recombination of any type of DNA.

Fluorescence in situ hybridization (FISH): is useful in microbial ecology, allows identification of particular bacterial groups in mixed samples AND depends on electron microscopy. uses virus hosts, uses a labeled probe, AND is useful in microbial ecology. uses a labeled probe, is useful in microbial ecology, AND allows identification of particular bacterial groups in mixed samples. uses a labeled probe, allows identification of particular bacterial groups in mixed samples, AND uses virus hosts. is useful in microbial ecology, allows identification of particular bacterial groups in mixed samples AND uses virus hosts.

uses a labeled probe, is useful in microbial ecology, AND allows identification of particular bacterial groups in mixed samples.

Host cells containing recombinant DNA can be selected on the basis of the properties of the: virus. enzymes. vector. introns. ribosomes.

vector.