Gel Electrophoresis Lab Analysis of Precut Lambda DNA

Restriction Enzymes Our lambda virus DNA samples have been precut with three different restriction enzymes. L – lambda DNA P – PstI lambda digest E – EcoRI lambda digest H – HindIII lambda digest

Running the Gel The phosphate groups in the sugar-phosphate backbone of DNA are negatively-charged. Molecules move through the gel at different rates, determined largely by their size and charge. Shorter molecules move through the gel faster than longer molecules.

Reasons for Each Step  Loading Dye Two sizes of blue molecules, small and large, help visualize movement of sample across gel.  Heat DNA Samples Denatures double stranded DNA to produce single strands that more easily move through gel.

 Tap Tubes on Table Top moves sample to bottom of tube for collection  Run the Gel in Chamber electrical field pulls negatively charged DNA through the gel, with distance moved proportional to size  Stain Overnight stain attaches to DNA within gel, making bands of DNA visible Reasons for Each Step

Lab Tips Follow the “How to Use a Micropipet” instructions at your station. –When finished, eject the tip into the disposal at your station. Carefully handle the DNA samples! Be sure your gel is well-side up and fully submerged in the buffer solution. Hold the micropipet just over the well. Be careful not to puncture the bottom of the well with the micropipet! Use tape to label which gel is yours (top or bottom).