Biology, Eighth Edition (Raven)

Chapter 24: Genome Evolution

Horizontal Gene Transfer

Can organisms get genetic information from any source other than their parents? One fundamental of Darwin’s theory of natural selection is that traits are passed from parents to offspring. The study of genetics has worked out many details of how characteristics are inherited. Geneticists have discovered that not all genes are passed from parents to offspring. Prokaryotic organisms in particular, can directly transfer DNA without reproduction or pick up DNA from the environment. Gene transfer that is divorced from reproduction is called horizontal gene transfer. Although, horizontal gene transfer is not as familiar as vertical gene transfer it is thought to have been a very important force in the early evolution of life on earth. It continues to be important in facilitating the evolution of modern bacteria.

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


1.	Vertical gene transfer...

		A)	is the transfer of DNA by mutation.
		B)	is the transfer of DNA by crossing over.
		C)	is the transfer of DNA between different genomes.
		D)	is the transfer of DNA during normal cell division.
		E)	is the transfer of DNA between tumor cells.

2.	Horizontal gene transfer...

		A)	is the transfer of DNA by mutation.
		B)	is the transfer of DNA by crossing over.
		C)	is the transfer of DNA between different genomes.
		D)	is the transfer of DNA during normal cell division.
		E)	is the transfer of DNA between tumor cells.

3.	The method used in horizontal gene transfer is...

		A)	gene splicing.
		B)	mutation.
		C)	crossing over.
		D)	homologous recombination.
		E)	nonhomologous recombination.

4.	Horizontal gene transfer is common and well understood.

		A)	True
		B)	False

5.	Horizontal gene transfer occurs frequently between the nuclear, mitochondrial, and chloroplast genomes of some eukaryotes.

		A)	True
		B)	False