Biology, Eighth Edition (Raven)

Chapter 20: Genes Within Populations

Electrophoresis

How does electrophoresis separate molecules? Electrophoresis is a versatile tool in molecular biology. There are many different types of electrophoresis but they all work on the same principle. Samples are placed on one end of a ‘gel’. The gel is a substance that consists of a molecular matrix of evenly sized and spaced openings. An electrical current is passed through the gel. The current moves the molecules in the sample through the gel. The rate at which the molecules move depends on both their size and their charge. Large molecules will be slowed by the matrix while small molecules will move more quickly. Molecules with a charge will move rapidly while uncharged molecules will move slowly.

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


1.	The first phase of 2-D gel electrophoresis separates proteins based on their_______.

		A)	mass
		B)	length
		C)	isoelectric point
		D)	density
		E)	none of the above

2.	The second phase of 2-D gel electrophoresis separates proteins based on their_______.

		A)	mass
		B)	length
		C)	isoelectric point
		D)	density

3.	At the end of a 2-D gel electrophoresis, proteins with a high mass would be found where?

		A)	along the left edge of the gel
		B)	along the right edge of the gel
		C)	along the top edge of the gel
		D)	along the bottom edge of the gel

4.	In the tube gel, each band represents a single type of protein.

		A)	True
		B)	False

5.	2-D gel electrophoresis may be used to isolate specific proteins for purification and additional study.

		A)	True
		B)	False