Gel Electrophoresis

1. Gel Electrophoresis Biotech I

2. Gel Electrophoresis • Definition: the process of separating molecules based on size and charge • Agarose: highly purified agar, heated and dissolved in buffer. Forms a matrix of pores for molecules to travel through. • Smaller molecules travel further • Molecules migrate towards the • positive (red) end of the chamber

3. Gel Electrophoresis • Process • Make Agarose gel • Thinner gels (0.8%) yield better results for larger DNA • Prepare samples • Restriction enzymes used to cleave at specified sites • Apply samples to gels, apply current • If samples run from positive end they will run off the gel • Stain gels to see bands • Would not be able to see bands if we did not stain

4. Gel Electrophoresis • DNA molecules have a negative charge • This allows them to migrate towards the positive end of the chamber • The samples and the electrophoresis chamber use specialized buffers. Using • TAE/TBE buffer helps stabilize the sample • and allows the reaction to occur quicker in • the chamber. • If water were in the chamber instead of TAE/TBE buffer the reaction would take much longer or migration may not occur at all • Stains: ethidium bromide will cause the bands to glow orange under UV light. Fast stain will result in blue bands

5. Uses for Gel Electrophoresis • DNA fingerprinting or profiling • Paternity testing • Crime scene sample analysis • Identification of bacteria and other pathogens • Who is credited with discovering the DNA profiling process? • Alec Jefferies in 1985