1. What is the main feature of a competent host cell in recombinant DNA technology?
A.
It can take up foreign DNA
B.
It can digest all DNA
C.
It can produce restriction enzymes only
D.
It can prevent DNA replication
Correct Answer:
It can take up foreign DNA
Explanation:
A competent host cell has the ability to receive and take up foreign DNA during transformation.
2. Which bacterium is commonly used as a competent host cell in recombinant DNA experiments?
A.
Escherichia coli
B.
Plasmodium
C.
Yeast only
D.
Influenza virus
Correct Answer:
Escherichia coli
Explanation:
Escherichia coli is commonly made competent and used as a host cell for introducing recombinant DNA.
3. Which chemical is commonly used to make bacterial cells competent?
A.
Calcium chloride
B.
Sodium chloride
C.
Glucose
D.
Ethanol
Correct Answer:
Calcium chloride
Explanation:
Calcium chloride treatment helps bacterial cells become competent to take up foreign DNA.
4. In the chemical method of transformation, competent bacterial cells are commonly exposed briefly to:
A.
Heat shock
B.
Freezing only
C.
Ultraviolet radiation
D.
Boiling for several minutes
Correct Answer:
Heat shock
Explanation:
A brief heat shock helps foreign DNA enter calcium chloride-treated competent bacterial cells.
5. What is the purpose of making a host cell competent?
A.
To enable uptake of recombinant DNA
B.
To destroy the vector
C.
To stop cell division permanently
D.
To remove the cell membrane completely
Correct Answer:
To enable uptake of recombinant DNA
Explanation:
Competence prepares the host cell to receive recombinant DNA from outside the cell.
6. Which method introduces DNA into cells by using a brief electrical pulse?
A.
Electroporation
B.
Centrifugation
C.
Filtration
D.
Sedimentation
Correct Answer:
Electroporation
Explanation:
Electroporation uses a brief electrical pulse to help DNA enter competent host cells.
7. During chemical transformation, competent bacterial cells are often kept on ice before heat shock because this:
A.
Supports the DNA uptake procedure
B.
Digests the plasmid DNA
C.
Kills all bacterial cells
D.
Removes the bacterial chromosome
Correct Answer:
Supports the DNA uptake procedure
Explanation:
Keeping competent cells on ice is part of the standard preparation and transformation procedure that supports DNA uptake.
8. What is introduced into a competent host cell during recombinant DNA technology?
A.
Recombinant DNA
B.
Only proteins
C.
Only lipids
D.
Cellulose fibers
Correct Answer:
Recombinant DNA
Explanation:
Competent host cells are used to receive recombinant DNA, usually carried on a suitable vector.
9. A bacterial cell that has taken up a plasmid from its surroundings is described as having undergone:
A.
Transformation
B.
Translation
C.
Transcription
D.
Respiration
Correct Answer:
Transformation
Explanation:
Transformation is the process in which a competent bacterial cell takes up foreign DNA such as a plasmid.
10. Which property is desirable in a host cell used for cloning recombinant DNA?
A.
Ability to accept and maintain foreign DNA
B.
Ability to destroy all plasmids
C.
Inability to grow in culture
D.
Complete absence of genetic material
Correct Answer:
Ability to accept and maintain foreign DNA
Explanation:
A useful competent host cell should be able to take up foreign DNA and maintain it so the inserted DNA can be propagated.
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