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

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.

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.)

DNA separation by gel electrophoresis large moderate small After electr

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.

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….