Question 1

Plasmid cloning vectors generally contain genes for which two traits? ​

Accepted Answer

The answer of Plasmid cloning vectors generally contain genes for...

Question 2

How do scientists determine the annealing temperature used in PCR reactions? ​

Accepted Answer

The annealing temperature in PCR is determined based on the melting temperature (Tm) of the primers, which can vary depending on their sequence and length. It is typically set a few degrees below the Tm to ensure specific binding.

Question 3

Taq polymerase is commonly used in PCR reactions because it ____. ​

Accepted Answer

Taq polymerase is a heat-stable DNA polymerase, meaning it can withstand the high temperatures needed for PCR reactions without denaturing, making it an ideal choice for these reactions.

Question 4

β-galactosidase is used in bacterial screening assays for visualization of colonies that contain recombinant DNA. What is its substrate? ​

Accepted Answer

The substrate for β-galactosidase is often X-gal, which is cleaved by the enzyme to produce a blue color indicating the presence of the recombinant DNA. Lactose is a common source of β-galactosidase, but it is not the substrate used for screening assays. Sucrose is not a substrate for β-galactosidase. LacZ is the gene that encodes for β-galactosidase, not a substrate. Agarose is not a substrate for β-galactosidase.

Question 5

PCR is ____. ​

Accepted Answer

PCR (Polymerase Chain Reaction) is a laboratory technique used to amplify a specific region of DNA through repeated cycles of denaturation, annealing, and extension by DNA polymerase. This results in the production of millions of copies of the DNA fragment of interest.

Question 6

Mass quantities of a target DNA sequence can be obtained by ____. ​

Accepted Answer

The answer of Mass quantities of a target DNA sequence...

Question 7

Why is it important to have an antibiotic resistance gene in plasmid cloning vectors? ​

Accepted Answer

The antibiotic resistance gene in plasmid cloning vectors allows researchers to distinguish bacteria that contain the plasmid from those that do not. This is important for selecting only the bacteria that have successfully taken up the recombinant vector.

Question 8

Which feature of a plasmid cloning vector is necessary for the plasmid to be replicated inside a host cell? ​

Accepted Answer

The origin of replication is necessary for the plasmid to be replicated inside a host cell, as it is the sequence where DNA replication begins.

Question 9

The key elements of a PCR reaction are ____. ​

Accepted Answer

The key elements of a PCR reaction include DNA with the target sequence to be amplified, a pair of primers to initiate DNA synthesis, the four nucleoside triphosphates (dATP, dCTP, dGTP, dTTP) as the building blocks of DNA, and DNA polymerase to synthesize the new DNA strands. DNA primase and agarose gel are not required for the PCR reaction itself, although agarose gel electrophoresis may be used to analyze the PCR products.

Question 10

The phases of each PCR cycle listed in order are ____. ​

Accepted Answer

The correct order of the phases in each PCR cycle is denaturation, annealing, and extension. During the denaturation phase, the double-stranded DNA template is heated to separate its two strands. During the annealing phase, the temperature is lowered to allow the primers to bind (anneal) to complementary sequences on each template strand approximating the region of interest. During the extension phase, the temperature is raised slightly and Taq polymerase binds to the primers and elongates the new strand by adding nucleotides, starting at the 3' end of the primer.

Question 11

During DNA cloning, why is the DNA of interest inserted into the middle of the lacZ+ coding sequence in the plasmid vector? ​

Accepted Answer

Inserting the DNA of interest into the lacZ+ coding sequence disrupts the gene, preventing the production of functional β-galactosidase. This allows researchers to use blue/white screening to distinguish bacteria with recombinant plasmids (white colonies) from those with non-recombinant plasmids (blue colonies).

Question 12

How is a DNA fragment containing a gene of interest generated for cloning? ​

Accepted Answer

The polymerase chain reaction (PCR) amplifies the DNA fragment from the genome, allowing for the gene of interest to be specifically targeted and amplified. This technique is commonly used for generating DNA fragments for cloning.

Question 13

When DNA fragments are sealed together by DNA ligase, the process is referred to as ____. ​

Accepted Answer

The process of sealing DNA fragments together using DNA ligase enzyme is called ligation. Therefore, the best choice is E, which is "ligation".

Question 14

Bacteria transformed with plasmids are plated on growth medium containing ampicillin and X-gal. White colonies on the plate contain bacteria with a ____ plasmid, meaning the lacZ+ gene is ____. ​

Accepted Answer

White colonies indicate that the lacZ+ gene is disrupted by the inserted DNA fragment, meaning the plasmid is recombinant.

Question 15

Bacteria transformed with plasmids are plated on growth medium containing ampicillin and X-gal. Blue colonies on the plate contain bacteria with a ____ plasmid, meaning the lacZ+ gene is ____. ​

Accepted Answer

The blue colonies indicate that the lacZ+ gene is intact, meaning the plasmid is nonrecombinant. The intact lacZ+ gene allows for the production of β-galactosidase, which cleaves X-gal to produce a blue color.

Question 16

What enables a PCR-amplified gene to be inserted into a cloning vector? ​

Accepted Answer

Restriction enzyme sites are often added to the 5' ends of primers used in PCR. This allows the PCR product to be cut with the same restriction enzyme as the cloning vector, facilitating the ligation of the PCR-amplified gene into the vector.

Question 17

Identify the correct steps for cloning a gene of interest, then arrange them in the correct order.
1.  Transform the bacteria.
2.  Incubate the DNA fragments and cut cloning vector with DNA ligase.
3.  Use restriction enzymes to cut the gene of interest and the cloning vector.
4.  Spread bacteria on medium containing lactose and ampicillin.
5.  Spread bacteria on medium containing X-gal and ampicillin.

Accepted Answer

The correct order is: 3. Use restriction enzymes to cut the gene of interest and the cloning vector, 2. Incubate the DNA fragments and cut cloning vector with DNA ligase, 1. Transform the bacteria, 5. Spread bacteria on medium containing X-gal and ampicillin.

Question 18

I need to determine if the gene for a particular protein is the same length in frogs, humans, and trees. Which method(s)will be most helpful to me? ​

Accepted Answer

PCR can amplify the specific gene of interest from each organism, and agarose gel electrophoresis can be used to compare the sizes of the amplified products to determine if they are the same length.

Question 19

Which component of the PCR reaction is responsible for its specificity? ​

Accepted Answer

The pair of DNA primers determines the specific region of DNA that will be amplified during PCR. These primers are designed to specifically bind to complementary sequences on opposite strands of the target DNA, allowing for selective amplification.

Question 20

A plasmid cloning vector and DNA fragments containing the XYZ gene, each digested with the same restriction enzyme, are mixed with DNA ligase. Which product(s)will result? ​

Accepted Answer

When plasmid vectors and DNA fragments are mixed with DNA ligase, a variety of products can form, including recombinant plasmids, nonrecombinant plasmids, and concatenated DNA fragments.

Quiz 18: Dna Technologies: Making and Using Genetically Altered Organisms, and Other Applications

Plasmid cloning vectors generally contain genes for which two traits?

How do scientists determine the annealing temperature used in PCR reactions?

Taq polymerase is commonly used in PCR reactions because it ____.

β-galactosidase is used in bacterial screening assays for visualization of colonies that contain recombinant DNA. What is its substrate?

PCR is ____.

Mass quantities of a target DNA sequence can be obtained by ____.

Why is it important to have an antibiotic resistance gene in plasmid cloning vectors?

Which feature of a plasmid cloning vector is necessary for the plasmid to be replicated inside a host cell?

The key elements of a PCR reaction are ____.

The phases of each PCR cycle listed in order are ____.

During DNA cloning, why is the DNA of interest inserted into the middle of the lacZ+ coding sequence in the plasmid vector?

How is a DNA fragment containing a gene of interest generated for cloning?

When DNA fragments are sealed together by DNA ligase, the process is referred to as ____.

Bacteria transformed with plasmids are plated on growth medium containing ampicillin and X-gal. White colonies on the plate contain bacteria with a plasmid, meaning the lacZ+ gene is .

Bacteria transformed with plasmids are plated on growth medium containing ampicillin and X-gal. Blue colonies on the plate contain bacteria with a plasmid, meaning the lacZ+ gene is .

What enables a PCR-amplified gene to be inserted into a cloning vector?

I need to determine if the gene for a particular protein is the same length in frogs, humans, and trees. Which method(s) will be most helpful to me?

Which component of the PCR reaction is responsible for its specificity?

A plasmid cloning vector and DNA fragments containing the XYZ gene, each digested with the same restriction enzyme, are mixed with DNA ligase. Which product(s) will result?