Simple Transposition

What are the effects of moving DNA from location in the genome to another? Transposable elements are DNA sequences that can change location. In some cases they can also copy themselves so that they can spread in the genome. Transposable elements are thought to be examples of parasitic DNA that use the functional genes in the genome as a mechanism for copying themselves. Insertion of a transposable element into the middle of a functional gene will usually result in the production of a nonfunctional protein. In other cases the transposable element may have no effect on the fitness of the organism. Prokaryotes have far fewer transposable elements than do eukaryotes indicating that they may have more efficient mechanisms for finding and removing genetic ‘freeloaders’.

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


1	Simple transposition is also termed ________ transposition.

		A)	direct
		B)	wholesome
		C)	conservative
		D)	liberal
		E)	complete

2	In simple transposition,

		A)	a double stranded piece of DNA is moved from one site to another.
		B)	a single strand is moved, leaving a single strand behind.
		C)	a double stranded piece of DNA is copied, and the copy is moved to another site.
		D)	a plasmid is incorporated into the cell’s chromosome.
		E)	viral DNA is incorporated into the cell’s chromosome.

3	The ends of a simple transposable element contain

		A)	sequences termed origins of transposition.
		B)	inverted repeats.
		C)	direct repeats.
		D)	self-replicating genes.
		E)	antibiotic-resistance genes.

4	The enzyme transposase catalyzes simple transposition.

		A)	True
		B)	False

5	In simple transposition, the transposable element ends up between two direct repeats of the target sequence.

		A)	True
		B)	False

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