Biology, Eighth Edition (Raven)

Chapter 24: Genome Evolution

Transposons: Shifting Segments of the Genome

How can transposons cause evolutionary changes? Transposons are segments of the genome that have the ability to both replicate themselves and to insert themselves elsewhere in the genome. The function of transposons is merely to replicate themselves. However they can potentially play an important role in evolution by copying and transferring other genetic material. There is evidence that transposons and their host genomes have co-evolved over long periods and that transposon activity may increase in response to environmental factors. The movement of transposons is a source that increases genetic variability. In particular, transposons contain regulatory genes that control transposon activity. It is thought that these regulatory genes may evolve to control other genes as well.

View the animation below, then complete the quiz to test your knowledge of the concept.


1.	Transposons are...

		A)	segments of messenger RNA.
		B)	transposable elements.
		C)	plasmids.
		D)	segments of DNA.
		E)	segments of transfer RNA.

2.	Transposons are...

		A)	transported by transduction.
		B)	transported by a sex pilus.
		C)	transported by conjugation.
		D)	transported by bacteriophages.
		E)	transported by plasmids.

3.	Which of the following is not true about transposons?

		A)	they are capable of shifting from one cell to another
		B)	they can move into the host genome
		C)	they can move from one site in the host genome to another site
		D)	is able to leave the host genome via a vector
		E)	replicate themselves before moving

4.	A transposon enters a bacterial cell by a bacteriophage.

		A)	True
		B)	False

5.	A transposon can move from the host DNA to a plasmid.

		A)	True
		B)	False