Biology, Eighth Edition (Raven)

Chapter 28: Prokaryotes

Bacterial Transformation

What eukaryotic genetic processes have similar features to transformation? Transformation has features in common with recombination and crossing over in meiosis. It is also shares features with regular DNA synthesis that occurs prior to both mitosis and meiosis. DNA is taken up from the environment. The external DNA binds to the same gene in the bacterial genome. The external gene is exchanged with the existing bacterial gene. In a sense this is equivalent to crossing over in meiosis. Homologous genes pair up and genetic material is exchanged between chromosomes. Bacteria are haploid organisms so crossing over does not occur during normal reproduction. Unlike meiosis the end product of this recombination is two mismatched strands. The same repair mechanisms used in DNA synthesis alter one of the strands so that it is complementary to the other strand.

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


1.	DNA transformation involves the transfer of DNA via

		A)	pili
		B)	naked DNA in solution
		C)	a restriction endonuclease
		D)	a bacteriophage

2.	The mismatch repair system will repair

		A)	only mismatching donor sequences
		B)	only mismatching recipient sequences
		C)	both sides of mismatching sequences
		D)	either the donor or the recipient strand

3.	When DNA from an ampicillin resistant organism is brought into an ampicillin sensitive organism by transformation and the product is grown on agar containing ampicillin

		A)	only the transformed cells will grow
		B)	only donor cells will grow
		C)	all cells grow
		D)	no cells grow
		E)	only ampicillin sensitive cells grow

4.	In transformation, both strands of donor DNA enter the recipient cell.

		A)	True
		B)	False

5.	Donor DNA is combined with recipient DNA by homologous recombination.

		A)	True
		B)	False