Gel Electrophoresis

By Erin Martin & Satya Moolani

What is gel electrophoresis?Gel electrophoresis is a method for separation and analysis of macromolecules (DNA, RNA and proteins) and their fragments, based on their size and charge.

Step 1: The DNA is cut by restriction enzymesRestriction enzymes are enzymes found in bacteria that cut DNA into fragments.

In the first example, the restriction enzyme is CCC/GGG which cuts the DNA and results in blunt ends.

In the second example, the restriction enzyme is G/AATTC which cuts the DNA and results in sticky ends.

Step 2: Electrical current separates the DNA piecesSince DNA is negatively charged, it will move from the well towards the bottom of the gel. The gel sorts the DNA molecules by size; smallest towards the bottom of the gel and larger toward the top since the smaller DNA molecules can move through the gel faster that the larger DNA molecules.

Step 3: Separated DNA pieces are transferred to a membrane

A method called southern blotting is used to transfer the DNA fragments onto a membrane.

Step 4: Chemicals make the bands visible During the preparation of the gel, a chemical is added to the gel that binds the DNA and makes the bands visible under a UV light.

Work Cited http://

www.geneticseducation.nhs.uk/laboratory-process-and-testing-techniques/gel-electrophoresis

https://www.addgene.org/plasmid-protocols/gel-electrophoresis/ https://en.wikipedia.org/wiki/Gel_electrophoresis https://en.wikipedia.org/wiki/Southern_blot