Question

Gel Question #1: During Lab 7, you and your three teammates performed gel electrophoresis as described in the lab manual. Your team was especially careful while carrying out the DNA barcoding procedures, following the protocols for sample digestion, DNA extraction, and PCR perfectly. You expect your results to look like the gel below (visualized under visible light on the left and UV light on the right): Student 1 Student 2 A1 P1 B1 col bd 165 A2P2B2 cos Abc 165 Student 3 Student 4 A3 P3 B3 A4 P4 B4 Col rbct 16S col bd 169 However, after performing gel electrophoresis, you get the following results (visualized under visible light on the left and UV light on the right): Student 1 Student 2 Student 3 Student 4

FULL image displayed under of the expected vs actual results of agarose gel analysis (the top picture is expected and bottom is the result)

Question: You conclude that the error occurred while preparing arose gel. What mistake was made? Why does it look like the picture above and not how you expected?

Answer 1

I reason behond such kind of results might be due to following reasons

1) looks like your gel has over run.. when you load the sample , you mix the sample with sample loading dye

This sample loading dye is containg bromo phenol blue as tracking dye. By using this dye we can track the movement of sample run.

When the gel run 3/ 4 or more by looking purple band we should stop the run and go for the analysis. But here looks like your lower gel purple bands exit the gel and might be some lower bands in your sample. This might be a reason of your such results.

2) Other reason may be your gel percentage. Percent of gel ( pore size) is depend on your DNA product. If you have to analyze small base sample than go fir higher percentage. If have large size DNA fragments than go for lower gel percentage.

For example if you want to see 60 _ 400 bp product go for 1-1.5% gel.

If 200 - 1000 bp = go for 1% gel.