Gel Electrophoresis Lab

The purpose of this experiment was to figure out the location and amount of cut marks that each restriction enzyme had compares to the next

The point of this lab is to determine who or what unidentified DNA belongs to. The three restriction enzymes, in this case are PstI, Hpal and SspI are set up on three different columns. Once the enzymes are loaded into the gels the enzymes undergo gel electrophoresis. This procedure makes the enzymes separate into their cuts. This allows a scientist to evaluate who or what the DNA belongs to based on the cut marks.

To begin this experiment we poured about 5mm of agarose solution into a casting tray. Then we scooped out a large bubble of debris and added to the side of the tray while it is still a liquid. Once the agarose has set, we placed the tray in the gel box so that the slots are at the negative end. Once the slots for the DNA are submerged completely, the DNA is ready to be loaded. We then carefully extracted small amounts of the DNA out of the tubes, and then steadily inserted them into the chambers of the gel. It is very important that the gel does not break at any time, for the experiment will be ruined. Once they are loaded, the electrophoresis box is closed and connected to electrical leads. After some time, due to the shocks from the voltage source, the DNA begins to move along the gel, splitting at certain points. After the DNA has split down the entire gel, we took it out and examined the DNA cuts and determine what the DNA belongs to.

After examining our gel, we noticed that the DNA had travelled to a different area than where we had initially put it.  The DNA of each moved toward the positive end of the gel.  This is because DNA is naturally negative due to the phosphate backbone so it wants to move opposite from the negative end of the gel and is attracted to the positive end.  Also, the distance travelled by each strand of DNA was different as well. This is in part due to the size of the strands.  Bigger strands of DNA tend to not move as much as the smaller ones due to the fact it is harder for something bigger to travel a long distance.  The bigger strands are unable to move through the gel as easily as the smaller ones; in a sense, they can't fit.  They were the ones closer to the wells or the initial positioning of the DNA.

Our experiment allows us to conclude about the effectiveness of gel electrophoresis when looking for a DNA match. Each band moves a different distance because restriction enzymes only cut at their specific protein recognition sites. 

The gels after the DNA had been added, inside the machine having electricity run through it

Finished gel after having been shocked