1. Below are a series of “compare and contrast” questions. As always, the answer
ID: 151979 • Letter: 1
Question
1. Below are a series of “compare and contrast” questions. As always, the answer may
be one, more than one (indicate which ones) or none.
A. Compare and contrast transformation, conjugation, and transduction.
a. Which involves the action of bacteriophages?
b. Which requires the binding of DNA fragments to the surfaces of “competent” cells?
c. Which can be used as a method for bacterial gene transfer in a laboratory setting?
d. Which requires direct contact between donor and recipient cells?
e. Which is the most common natural method for transferring plasmids between cells?
f. In which form of gene transfer is the host cell typically killed?
Explanation / Answer
Let us define the three terms first. They are means of horizontal gene transfer.
Transformation: It is the genetic alteration of a cell due to the direct uptake and incorporation of external genetic material from its surroundings through the cell membrane. For transformation to take place, the recipient bacteria must be competent.
Transduction: Transduction is the process by which foreign DNA is introduced into a cell by a virus.
Conjugation: It is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells.
a. Transduction involves bacteriophages.
b. Competence is nothing but the ability of a cell to take up external DNA which is in contact with the cell membrane. Transformation requires the cells to be competent so that they may take up DNA.
c. All three methods can be used for bacterial gene transfer in a lab.
d. In conjugation, a conjugation bridge is formed between the two bacterial cells so they must have direct contact.
e. Conjugation is the most common method for transferring plasmids between the cells
f. Transformation. The host cell releases it's DNA into the environment upon death. This DNA is taken up by other cells.
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