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