Notes

Outline

How can Gel-Electrophoresis help in the identification of Dna?

Slide 2

The Principles of Gel Electrophoresis DNA is a negatively charged molecule. If put into an electric field, it will move from the negative to the positive pole. A gel serves as the matrix for the movement of the DNA molecule. The gel is a semisolid material with certain size pores. DNA is cut into fragments of different size. The smaller ones are able to move faster through the pores of the gel than the larger ones. This creates a pattern where the fragments are arranged according to their size from the negative to the positive pole.

Slide 4

How are DNA fragments generated? DNA is cut using restriction enzymes. Examples for different restriction enzymes:  Eco RI, Hind III Restriction enzymes cut DNA at specific four or six-base-pair-sequences called restriction sites. Examples for different restriction sites: Eco RI  at G AATT C                  C TTAA G Hind III at A AGCT T                  T TCGA A

Slide 6

Why does it work? Each individual has a slightly different base pair sequence in its DNA. Restriction enzymes create different size fragments for different individuals. If put into an electric field on a gel, restricted DNA will create a pattern that is specific to this individual.