1. Thanks to Cal State LA! Kuhn/Pickett
Gel Electrophoresis
Thanks to Cal State LA!
Kuhn/Pickett

2. Electrophoresis
1. Gel electrophoresis separates DNA and RNA molecules according to size, shape and topological properties
DNA is placed in a Gel matrix, which is an jello-like porous material that support and allows macromolecules like DNA to move through. Agarose and polyacrylamide are two different gel matrices.

3. Electrophoresis
DNA and RNA molecules are negatively charged, thus move in the gel matrix toward the positive pole (+)
Linear DNA molecules are separated according to size.
The DNA molecules are stained before being placed in the gel matrix to allow for easy viewing of the movement of the different-sized fragments. (DNA is in nature a clear substance like snot.)

4. DNA separation by gel electrophoresis
large
moderate
small
After electr

5. Restriction endonucleases cleave DNA molecules at particular sites
Nucleic acid
Restriction digestion
Restriction endonucleases cleave DNA molecules at particular sites
Why use endonucleases?
--To make large DNA molecules break into manageable fragments. Otherwise, the DNA would remain in one large strand.

6. Restriction digestion
Restriction endonucleases: the nucleases that cleave DNA at particular sites by the recognition of specific sequences
The target site recognized by endonucleases is usually palindromic.
e.g. EcoRI
Because everyone has slightly different
DNA, when a specific strand is cut by a given
endonuclease, it will generate
fragments of different lengths.
5’….GAATTC.….3’
….CTTAAG….