MCB chapter 9 mastering
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
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
In which direction does DNA polymerase synthesize the new DNA strand?
5' to 3'
In the figure, after digestion with the appropriate restriction enzyme, what is the smallest piece containing the entire ampicillin-resistance (amp) gene?
1.50kbp
What is the temperature used for the extension step?
72
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
What is the sequence of the temperatures of a typical PCR reaction?
94 °C, 60 °C, 72 °C
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. Submit
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
Recombinant DNA techniques typically involve generating a clone. Why?
Producing a clone generates many copies of the gene of interest.
Which of the following attaches the target gene to a desired location?
DNA ligase
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
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.
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
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
Which statement best describes restriction enzymes?
They are important for cloning applications because they can be used to cut DNA at specific nucleotide sequences.
What is the function of the primers in PCR?
They provide a 3' end for the DNA polymerase
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
Which of the following best describes a clone in the context of genetic modification procedures?
a culture of genetically identical cells
A restriction fragment is
a segment of DNA
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.
Which of the following best describes why a vector is used in genetic modification procedures?
cells usually won't copy an isolated gene sequence
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
Which of the following is an advantage of using E. coli to make a human gene product?
its genes are well known
Which of the following is NOT a desired characteristic of DNA vectors used in gene cloning procedures?
large size
PCR stands for
polymerase chain reaction
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
PCR can be used to identify an unknown bacterium because
the RNA primer is specific
how do restriction enzymes cut DNA sequences
they cut DNA at sites, called recognition sites, that have specific nucleotide sequences
What is the end goal of PCR?
to quickly increase the number of copies of a specific DNA sequence
In recombinant DNA technology, a vector is a self-replicating segment of DNA, such as a plasmid or viral genome.
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
Self-replicating DNA used to transmit a gene from one organism to another is a
vector