MicroMastering Ch9
A source of heat-stable DNA polymerase is
Thermus aquaticus.
Which of the following is NOT a property of useful vectors?
They always contain only one gene.
In the figure, the bacteria transformed with the recombinant plasmid and plated on media containing ampicillin and X-gal will
form white, ampicillin-resistant colonies
The Bt toxin derived from Bacillus thuringiensis has been introduced into some crop plants to make them resistant to insect destruction. True or False
true
Biotechnology involves the
use of microorganisms to make desired products, the use of animal cells to make vaccines, and the development of disease-resistant crop plants.
Of the following components, which ones are required for the amplification of a specific section of DNA using the polymerase chain reaction?
-DNA primers -DNA polymerase that is heat stable
Rank the typical genetic modification procedure from first step to last step. To rank items as equivalent, overlap them.
-Isolate bacterial plasmid -select gene of interest + insert into plasmid -plasmid take up by bacterium -bacteria replicate -protein product harvested from bacteria & cloned gene harvested from bacteria
GM crops have raised issues among communities in which they are produced. Which of the following are concerns raised by the public about genetically engineered crops?
-The Bt toxin could negatively affect the taste of the food that is produced from these crops. -The Bt toxin could result in the death of non-pest species of insects. -The Bt gene could ultimately make the plants pathogenic to humans.
In a laboratory setting, which of the following scenarios would benefit from utilizing a technique such as PCR?
-You would like to make copies of a bacterial gene of interest for sequencing and characterization. -You have a fastidious organism that is hard to grow in large numbers and you need to isolate an operon for transferring to a bacterium for expression. -You want to study the effects of a protein on different cell types, but the bacterial species that the protein originates from is considered a pathogen.
Which plasmid characteristics would be required for optimal expression of a DNA fragment to yield a peptide?
-a region with multiple sites for restriction digestion with different enzymes -a strong promoter for expression of the inserted DNA fragment -a DNA sequence that signals for trafficking of the plasmid to the nucleus
Which of the following places the steps in the PCR procedure in the correct order? 1) Incubate at 94°C to denature DNA strands; 2) Incubate at 72°C for DNA synthesis; 3) Incubate at 60°C for primer hybridization.
1,3,2
The following tiles indicate the first five thermocycler steps in a PCR run. Arrange them in the correct order.
1. 94C 1 min 2. 55C 1 min 3. 72C 1 min 4. 94C 1 min 5. 55C 1 min
In the figure, after digestion with the appropriate restriction enzyme, what is the smallest piece containing the entire ampicillin-resistance (amp) gene?
1.50kbp
How many pieces will EcoRI produce from the plasmid shown in the figure?
2
Each step of the polymerase chain reaction is associated with a particular temperature.What are they?
55C-primer annealing 72C-DNA extension 94C-DNA denaturation
The following steps must be performed to make a bacterium produce human protein X. 1-Translation 2-Restriction enzyme 3-Prokaryotic transcription 4-DNA ligase 5-Transformation 6-Eukaryotic transcription 7-Reverse transcription Which of the following places the steps in the correct order?
6,7,2,4,5,3,1
What is the temperature used for the extension step?
72C
You have a small gene that you wish replicated by PCR. After 3 replication cycles, how many double-stranded DNA molecules do you have?
8
The restriction enzyme EcoRI recognizes the sequence GAATTC. Which of the following is TRUE of DNA after it is treated with EcoRI?
All of the DNA fragments will have single-stranded regions ending in AA.
Scientists like to use fluorescent proteins for various types of recombinant DNA procedures. You have a very small amount of the gene for a fluorescent protein. You'd like to make a fluorescent bacterium. Which of the following represents the correct sequence of procedures that you would use?
Amplify the gene using PCR. Insert the gene into a plasmid vector. Transform the vector into the bacteria.
Which of the following best describes how recombinant DNA technology currently helps patients who do NOT produce adequate amounts of growth hormone (hGH)—a condition that otherwise leads to stunted growth?
Bacteria now produce hGH.
Which of the following best describes why a vector is used in genetic modification procedures?
Cells usually won't copy an isolated gene sequence.
Which of the following methods could be used to identify the source of an outbreak?
DNA fingerprinting
Which of the following are used by the Centers for Disease Control and Prevention to track outbreaks of foodborne disease?
DNA fingerprints, restriction fragment length polymorphisms, and reverse-transcriptase PCR(rtPCR)
Which of the following attaches the target gene to a desired location?
DNA ligase
Suppose the thermocycler is INCORRECTLY programmed to omit the 72∘∘C step in each cycle of an otherwise normal PCR run. Which of the following would most likely occur?
DNA polymerase would synthesize DNA more slowly
What provides the energy for DNA polymerization in a PCR reaction?
Deoxyribonucleoside triphosphates
After the 94∘∘C step, why must the thermocycler reduce the temperature to 55∘∘C?
To allow primers to bind to the DNA template strands
Which of the following best describes why PCR protocols contain numerous cycles of the denaturation/annealing/extension steps?
Each cycle of PCR doubles the amount of DNA synthesized, but the number of copies starts out small. Numerous cycles are required to produce a sufficient number of copies.
Bt crops, including potatoes and cotton, are genetically engineered using laboratory techniques. Which of the following utilizes recombinant DNA technology to produce advantageous traits in the crops that are produced?
Genetically engineered crops have an advantageous gene from another organism inserted into their genome.
Bt crops are engineered in the lab to produce Bt toxins due to the presence of a bacterial gene from B. thuringiensis. Why is it advantageous for the plants to produce the Bt toxin?
Insects that normally destroy non-toxin-producing crops will be killed when they eat plants that do produce the toxin
Why would a recombinant DNA molecule be inserted into a host cell?
It can be copied, transcribed, and translated into a desired protein.
Why is DNA polymerase from Thermus aquaticus ideal for PCR?
It can withstand the high temperatures associated with PCR.
Which of the following statements about recombinant DNA technology is FALSE?
It has limited application because genes of interest cannot be moved from one type of cell to another.
You want to determine whether a person has a certain mutant gene. The process involves using a primer and a heat-stable DNA polymerase. This process is
PCR
Why is PCR a valuable technique?
PCR creates large amounts of DNA from minute source quantities.
Recombinant DNA techniques typically involve generating a clone. Why?
Producing a clone generates many copies of the gene of interest.
Which of the following are used to silence specific genes and hold promise for treating cancer or viral diseases, such as hepatitis B?
RNA interference (RNAi)
Which of the following is an application that uses PCR?
Sequencing a gene, diagnosing a disease, and providing enough DNA for cloning into another organism
What does a thermocycler do?
Subjects samples to temperature changes
Which of the following best explains how scientists are able to introduce the bacterial gene for Bt toxin into the cotton plant genome?
The Bt toxin gene is isolated and inserted into a Ti plasmid from Agrobacterium tumefaciens. The engineered Ti plasmid is taken up by a bacterium that infects the cotton plant.
How do the strands separate during PCR?
The high heat of the denaturation step breaks the hydrogen bonds between the two strands.
What is a thermocycler?
The machine that controls the heat of the reaction, cycling between the different temperatures of the different steps during PCR
Which statement best describes restriction enzymes?
They are important for cloning applications because they can be used to cut DNA at specific nucleotide sequences.
How do restriction enzymes cut DNA sequences?
They cut DNA at sites, called recognition sites, that have specific nucleotide sequences.
In general, how might recombinant DNA technology be used to prevent a genetic disorder caused by a mutation in a single gene?
To insert a desirable gene, remove an undesirable gene, or replace a defective gene with a functioning gene
Which of the following best describes the purpose of primers in PCR?
To provide a structure from which DNA can be synthesized
What is the end goal of PCR?
To quickly increase the number of copies of a specific DNA sequence
What is the function of the primers in PCR?
What is the function of the primers in PCR?
why is baker's yeast useful for expressing genetically engineered genes?
Yeast cells are eukaryotic and so would likely be successful in expressing eukaryotic genes.
Which of the following best describes a clone in the context of genetic modification procedures?
a culture of genetically identical cells
In PCR, it is important to use Taq DNA polymerase, as opposed to other DNA polymerases. This is because Taq is capable of synthesizing DNA _________.
after exposure to 94∘∘C
Restriction enzymes are
bacterial enzymes that destroy phage DNA.
The Ti plasmid isolated from Agrobacterium can be used to insert DNA into any type of plant. True or False
false
The Human Genome Project, which was completed in 2003, was focused on
determining the nucleotide sequence of the entire human genome.
The use of an antibiotic-resistance gene on a plasmid used in genetic engineering makes
direct selection possible.
Foreign DNA can be inserted into cells using a variety of different methods. Which method involves the formation of microscopic pores in the cell's membrane?
electroporation
Which of the following pairings of recombinant DNA techniques and applications does NOT match?
gene silencing: production of subunit vaccines
If you have inserted a gene in the Ti plasmid, the next step in genetic engineering is
inserting the Ti plasmid into Agrobacterium.
Which of the following is an advantage of using E. coli to make a human gene product?
its genes are well known
An advantage of cDNA over genomic DNA is that it
lacks introns
Which of the following is NOT a desired characteristic of DNA vectors used in gene cloning procedures?
large size
The reaction catalyzed by reverse transcriptase is
mRNA → cDNA.
The use of "suicide" genes in genetically modified organisms is designed to
prevent the growth of the modified organisms in the environment.
A restriction fragment is
segment of DNA
Assume you have discovered a cell that produces a lipase that works in cold water for a laundry additive. You can increase the efficiency of this enzyme by changing one amino acid. This is done by
site-directed mutagenesis
In an effort to yield a high percentage of transformed bacteria, you may choose to utilize electroporation to increase the probability of what occurring?
that nearly all of the cells present in the field will take up at least one copy of the plasmid
In recombinant DNA technology, a vector is a self-replicating segment of DNA, such as a plasmid or viral genome. True or False
true
One of the first commercial successes of recombinant DNA technology was the production of human insulin using genetically engineered E. coli. True or False
true
PCR can be used to identify an unknown bacterium because
the RNA primer is specific.
Which of the following methods would be used to introduce the plasmid shown in the figure into E. coli?
transformation
Which of the following processes is NOT involved in making cDNA?
translation
Self-replicating DNA used to transmit a gene from one organism to another is a
vector