Question 1

Recombinant DNA technology requires not only getting the DNA into a cell,but also getting it to replicate appropriately.In this process,the specificity of which enzyme can present a challenge?
A) DNA polymerase
B) DNA ligase
C) RNA polymerase
D) Reverse transcriptase
E) Replicase

Accepted Answer

DNA polymerase is responsible for replicating DNA in the cell. However, in recombinant DNA technology, foreign DNA may contain sequences that the cell's DNA polymerase cannot recognize or replicate properly. This can present a challenge in ensuring that the foreign DNA is replicated accurately in the host cell.

Question 2

A biologist would most likely use the technique of electroporation to
A) separate proteins based on size and charge.
B) knock out a gene.
C) create antisense DNA.
D) measure expression levels of a gene.
E) insert DNA into host cells.

Accepted Answer

Electroporation is a technique commonly used to introduce DNA or other charged molecules, such as RNA or proteins, into host cells. By applying an electric field to a solution containing the cells and DNA, the cell membrane briefly becomes permeable, allowing the DNA to enter the cell. This technique is used in a variety of applications, including genetic engineering, gene therapy, and the production of transgenic organisms.

Question 3

Which plasmid would allow a researcher to visually select a bacterial colony that has a recombinant plasmid using white light? [Note: The plasmid also has selectable reporter gene for ampicillin resistance (amp^r)outside of the cloning site.] A) A plasmid with the gene for X-gal in the cloning site B) A plasmid with the gene for green fluorescent protein (GFP)outside of the cloning site C) A plasmid with the LacZ reporter gene outside of the cloning site D) A plasmid with the LacZ reporter gene in the cloning site E) A plasmid with the green fluorescent protein (GFP)within the cloning site

Accepted Answer

A plasmid with the LacZ reporter gene in the cloning site allows for blue/white screening. When a gene is inserted into the LacZ site, it disrupts the gene, resulting in white colonies, indicating successful recombination.

Question 4

A restriction enzyme cuts a 25,700 bp segment of DNA into three fragments.Fragment A is 5,800 bp and fragment B is 6,600 bp.How long is fragment C,and which of the fragments will move the farthest in an electrophoresis gel?
A) 12,400 bp;fragment A
B) 12,400 bp;fragment C
C) 13,300 bp;fragment A
D) 13,300 bp;fragment C
E) 19,900 bp;fragment C

Accepted Answer

Fragment C is 13,300 bp (25,700 - 5,800 - 6,600). In electrophoresis, smaller fragments move farther, so fragment A (5,800 bp) will move the farthest.

Question 5

An important vector for the manipulation of plant genes comes from the bacterium A.tumefaciens and is called
A) an EcoRI plasmid.
B) $\lambda$ bacteriophage.
C) BamHI.
D) Ti plasmid.
E) a LacZ plasmid.

Accepted Answer

The Ti (tumor-inducing) plasmid of Agrobacterium tumefaciens is widely used as a vector for the introduction of foreign genes into plants, particularly for genetic engineering of crops. The Ti plasmid naturally transfers DNA into plant cells, and this process has been engineered to deliver genes of interest into the plant genome.

Question 6

Which characteristic makes plasmids useful as a vector?
A) Many plasmids contain genes that convey antibiotic resistance.
B) Unlike viruses,plasmids do not need to be coaxed by artificial means to infect cells.
C) Plasmids can accommodate a large amount (over 100 kb)of DNA.
D) Plasmids use the same origin of replication as eukaryotic cells.
E) A cell can only host one plasmid at a time.

Accepted Answer

Plasmids often contain antibiotic resistance genes, which allow for the selection of successfully transformed cells by growing them in the presence of the antibiotic.

Question 7

Why are plant cells particularly useful as hosts for recombinant DNA?
A) Animal cells cannot be cultured.
B) Plant cells lack introns.
C) Plant cells can be dedifferentiated into stem cells.
D) Plant cells have reverse transcriptase.
E) Plant cells have plasmids.

Accepted Answer

Plant cells can be dedifferentiated into stem cells, which means they have the ability to undergo cell division and differentiate into different cell types. This makes them useful hosts for recombinant DNA because they can be transformed with foreign DNA and allow for production of recombinant proteins. Additionally, plant cells are easy to culture, have a cell wall that helps protect the DNA from degradation, and have a large central vacuole that can be used for protein storage.

Question 8

To replicate within the cells of a host,recombinant DNA must either _______ into the host's genome or contain a(n)_______.Otherwise,the recombinant DNA would not be replicated,since _______ requires specific sequences to bind to DNA.
A) integrate;origin of replication;DNA polymerase
B) integrate;vector;DNA polymerase
C) recombine;origin of replication;DNA ligase
D) recombine;stop transcription signal;DNA polymerase
E) integrate;stop transcription signal;DNA ligase

Accepted Answer

To replicate within the cells of a host, recombinant DNA must integrate into the host's genome or contain an origin of replication. Integration requires the enzyme DNA ligase whereas DNA polymerase is involved in the replication process. choice B is incorrect because the vector is the means by which the recombinant DNA is introduced into the host cell, not a requirement for replication. Recombination is not a requirement for replication, making choice C incorrect. Stop transcription signals are involved in gene expression and have no role in replication, so choices D and E can be eliminated.

Question 9

Which characteristic would not be useful in a vector?
A) Multiple unique restriction enzyme recognition sequences
B) Antibiotic resistant gene
C) The ability to replicate independently inside the host cell
D) Visual reporter gene
E) Large size relative to the host chromosomes

Accepted Answer

A vector should be small to ensure efficient transfer and replication within the host cell. A large size would hinder these processes.

Question 10

The production of many copies of a particular gene is called
A) transfection.
B) restriction.
C) cloning.
D) annealing.
E) inducing.

Accepted Answer

Cloning involves the production of many copies of a particular gene. Transfection is the process of introducing foreign DNA into eukaryotic cells. Restriction is the process of cutting DNA at specific sites using restriction enzymes. Annealing is the process of joining two complementary DNA strands. Inducing is the process of causing a particular gene or process to occur.

Question 11

The process of inserting recombinant DNA is considered transfection when
A) the host cells are mouse tissue culture cells.
B) the host cells are E.coli cells.
C) the host cells are yeast cells.
D) the vector lacks a replicon.
E) a selectable marker is used.

Accepted Answer

Transfection specifically refers to the introduction of foreign DNA into eukaryotic cells, such as mouse tissue culture cells.

Question 12

In the construction of a transgenic cell,a gene that enables growth on arabinose is added to the vector.This gene is being used as a
A) reporter gene.
B) replicon.
C) cloning vector.
D) blunt end.
E) expression vector.

Accepted Answer

The answer of In the construction of a transgenic cell,a...

Question 13

Use the following to answer questions :
Suppose one restriction enzyme (enzyme A)makes two cuts in a linear DNA fragment and another restriction enzyme (enzyme B)makes one cut in that same DNA.The cuts are not in the same place,and none of the cut fragments are exactly the same size.The restriction digest is set up on an electrophoresis gel.
-How many bands should the gel pick up if both enzymes A and B are used in the restriction digest?
A) Two
B) Three
C) Four
D) Five
E) Six

Accepted Answer

Enzyme A cuts the linear DNA fragment at two different places, which would result in three fragments of different sizes. Enzyme B cuts the same DNA fragment at one place, which would result in two fragments of different sizes. Therefore, when both enzymes A and B are used, there will be a total of four bands on the electrophoresis gel.

Question 14

Which enzyme would be used to join two DNA fragments?
A) Reverse transcriptase
B) DNA polymerase
C) DNA recombinase
D) DNA endonuclease
E) DNA ligase

Accepted Answer

DNA ligase is the enzyme responsible for joining two DNA fragments together by catalyzing the formation of a phosphodiester bond between the adjacent nucleotides on each strand of DNA. Reverse transcriptase and DNA polymerase are involved in DNA synthesis, while DNA recombinase and DNA endonuclease are involved in cutting and rearranging DNA sequences, not joining them together.

Question 15

In gel electrophoresis,one can determine the relative abundance of a fragment by
A) examining how quickly it moves on the gel;the fastest moving fragments are the most abundant.
B) examining how quickly it moves on the gel;the slowest moving fragments are the most abundant.
C) examining the intensity of the band.
D) using DNA ligase.
E) using a selectable marker.

Accepted Answer

The relative abundance of a fragment can be determined by examining the intensity of the band on the gel after electrophoresis. The more intense the band, the more abundant the fragment. A and B are incorrect because the speed at which a fragment moves on the gel is dependent on its size and charge, not its abundance. D and E are not relevant to gel electrophoresis as they involve different techniques.

Question 16

Which characteristic is not one of the properties of yeast cells that have made them useful eukaryotic hosts for recombinant DNA studies?
A) Their rapid rate of cell division
B) Their small genome size
C) Their ease of growth in the laboratory
D) Their ability to ferment alcohols
E) Their similarity to most other eukaryotic cells

Accepted Answer

The ability to ferment alcohols is not a property of yeast cells that makes them useful eukaryotic hosts for recombinant DNA studies. Other options such as rapid rate of cell division, small genome size, ease of growth in the laboratory, and similarity to most other eukaryotic cells are important characteristics that make yeast cells useful hosts for genetic engineering.

Question 17

Transgenic cells are created via the _______ of recombinant DNA into cells.
A) recombination
B) transfection
C) ligation
D) restriction
E) complementation

Accepted Answer

Transgenic cells are created via transfection, which is the process of introducing recombinant DNA into cells. Recombination, ligation, and restriction are all steps within the process of creating recombinant DNA, but not specifically the creation of transgenic cells. Complementation is a process in which a non-functional gene is complemented by a functional gene, but not related to transgenic cell creation.

Question 18

There are some limitations to the use of bacteria as hosts in studies of eukaryotic gene expression because
A) bacteria are haploid.
B) transcription works differently in bacteria and in eukaryotes.
C) bacteria have a small genome size.
D) eukaryotes contain plasmids.
E) bacteria lack genetic markers.

Accepted Answer

Transcription works differently in bacteria and in eukaryotes, so using bacteria as hosts may not accurately reflect eukaryotic gene expression. Additionally, bacteria and eukaryotes have different post-transcriptional processing mechanisms, such as splicing in eukaryotes, which bacteria do not have.

Question 19

Suppose a DNA fragment from a human gene has been cut such that it has sticky ends.A DNA fragment from bacteria with sticky ends complementary to those of the human DNA is added to the mix.What would prevent the complementary ends of the human DNA from rejoining,and thus prevent the formation of a recombinant DNA molecule?
A) DNA ligase
B) Restriction endonuclease EcoRI
C) Reverse transcriptase
D) A cloning vector
E) Nothing

Accepted Answer

The complementary sticky ends of the human and bacterial DNA can naturally anneal, and nothing would inherently prevent them from joining unless specific inhibitors or conditions are introduced.

Question 20

Two plasmids are used in a recombinant DNA procedure.Plasmid 67A carries a gene for resistance to the antibiotic ciprofloxacin,and plasmid 65B carries a gene for resistance to the antibiotic tetracycline.The plasmids are cut with HindIII restriction endonuclease,and then mixed with DNA ligase.In this procedure,what is the role of tetracycline?
A) It enhances transformation.
B) It is a selectable marker.
C) It is a vector.
D) It ligates the DNAs.
E) It provides color to the bacterial colonies.

Accepted Answer

Tetracycline acts as a selectable marker, allowing for the identification and selection of bacterial colonies that have taken up the plasmid carrying the tetracycline resistance gene. Those colonies that have not taken up the plasmid will not survive in the presence of tetracycline.

Quiz 13: Biotechnology

Recombinant DNA technology requires not only getting the DNA into a cell,but also getting it to replicate appropriately.In this process,the specificity of which enzyme can present a challenge?

A biologist would most likely use the technique of electroporation to

Which plasmid would allow a researcher to visually select a bacterial colony that has a recombinant plasmid using white light? [Note: The plasmid also has selectable reporter gene for ampicillin resistance (amp^r) outside of the cloning site.]

A restriction enzyme cuts a 25,700 bp segment of DNA into three fragments.Fragment A is 5,800 bp and fragment B is 6,600 bp.How long is fragment C,and which of the fragments will move the farthest in an electrophoresis gel?

An important vector for the manipulation of plant genes comes from the bacterium A.tumefaciens and is called

Which characteristic makes plasmids useful as a vector?

Why are plant cells particularly useful as hosts for recombinant DNA?

To replicate within the cells of a host,recombinant DNA must either ___ into the host's genome or contain a(n) _.Otherwise,the recombinant DNA would not be replicated,since _____ requires specific sequences to bind to DNA.

Which characteristic would not be useful in a vector?

The production of many copies of a particular gene is called

The process of inserting recombinant DNA is considered transfection when

In the construction of a transgenic cell,a gene that enables growth on arabinose is added to the vector.This gene is being used as a

Which enzyme would be used to join two DNA fragments?

In gel electrophoresis,one can determine the relative abundance of a fragment by

Which characteristic is not one of the properties of yeast cells that have made them useful eukaryotic hosts for recombinant DNA studies?

Transgenic cells are created via the _______ of recombinant DNA into cells.

There are some limitations to the use of bacteria as hosts in studies of eukaryotic gene expression because