Cool Gel Electrophoresis Lab

Intro: 

During the lab, we take DNA samples containing combinations of restriction enzymes and run them through a gel electrophoresis. The overall goal of the lab is to analyze the DNA bands in the gel to approximate the sizes of the DNA fragments and being able to construct a plasmid map that correctly places enzymes in the appropriate location with respect to the gel's data. 

The Gel Process:

Once given a premade gel mold, we load our five DNA samples in 5 of the 6 slots after placing it in the water. The first slot contains Lambda which is the control DNA and is free of restriction enzymes. This will be our template for determining the sizes of the DNA fragments. The second slot is left empty. The third contains restriction enzyme PST1, the fourth contains PST1/ SSP1, the fifth contains PST1/ HPA1, and the final slot contains all three restriction enzymes. 

Once we let the process run and the DNA fragments run towards the positive end because they are negatively charged, we get a gel that looks like this. 

Using the lambda as the template, and using other people's gel for further measurement, we are able to accurately label the DNA fragments with the appropriate size. The smaller fragments are further from the starting point because they are smaller in size and can travel further than the larger fragments. We start to see pattern in each gel slot and all of the slots add up the the same number of base pairs, 4100 bp. With all of this data, we can now construct our plasmid map. 

Mapping the Plasmid:

After a good ol' round of gel electrophoresis, there's nothing better than mapping out your plasmid and its restriction enzyme cuts. Seriously though, pay attention because this is pretty slick. First we examine the second gel lane, which was cut up by none other than PstI. From this lane our circular DNA is cut into two pieces, approximately 600 and 3500 base pairs long when compared to the lambda pieces, which means that PstI, must have cut the plasmid twice as such...

Then we examine the third lane, wherein our friendly neighborhood plasmid was cut by both PstI and HpaI. We get fragments that are 600, 500, and 3000 base pairs long, which means that our 4100bp fragment from the second lane was cut into two pieces by HpaI. We get the following result...

Then we check out the fourth lane where we used PstI and SspI to cut the plasmid. We get fragments that are 600, 1300, and 2200 base pairs long, which means our 3000bp fragment from lane two was cut into two fragments by SspI. Here's our plasmid now...

Lastly, when we use all three restriction enzymes to cut up the plasmid at the same time, as in lane five, we get the following cuts...

So there you have it, a hypothetical outline of how our restriction enzymes work on our plasmids based on our gel electrophoresis. Next time you want to commit a crime, remember that technology like this is legit, and it gets people incarcerated on the regular.