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MCAT Content / Viral Life Cycle / Transduction Transfer Of Genetic Material By Viruses

Transduction: transfer of genetic material by viruses

Topic: Viral Life Cycle

In transductionbacteriophages move short pieces of chromosomal DNA from one bacterium to another “by accident.”

Bacteriophages, like other viruses, commandeer a cell’s resources and use them to make more bacteriophages. However, this process can be a little sloppy. Sometimes, chunks of host cell DNA get caught inside the new bacteriophage as they are made. When one of these “defective” bacteriophages infects a cell, it transfers the DNA. Some bacteriophages chop the DNA of their host cell into pieces, making this transduction more likely.

Transduction does not require physical contact between the cell donating the DNA and the cell receiving the DNA. It is also a common technique employed by scientists to introduce foreign genes into cells for research.


In the image above it can be seen that in step 1, the bacteriophage infects the bacterial cell with viral genetic material. This causes the bacterial cell in step 2 and 3 to reproduce the viral protein and genetic material to make viral copies. However, when these new bacteriophages are made, some of them contain DNA from the host bacterial cell. In step 4 the bacteriophage contains DNA from a bacterial source and in step 5 and 6 when it infects a bacterial cell this extra bacterial genetic material is incorporated into the host cells DNA, transferring genetic material from one bacterial cell to another.

Practice Questions

Khan Academy

Virulence factors in outbreak-strain cholera

 MCAT Official Prep (AAMC)

Key Points

• Transduction is the introduction of one bacteria’s genetic material into another through a bacteriophage

• This occurs when new bacteriophages are made in the host cell, and their host’s DNA is accidentally taken up in the process

Key Terms

bacteriophage: viruses that infect bacteria

transduction: injection of foreign DNA by a bacteriophage virus into the host bacterium

DNA: deoxyribonucleic acid, genetic material

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