Tuesday, March 10, 2015

Restriction mapping of plasmid DNA

Purpose: The purpose of this lab was to characterize a DNA sequence.

Introduction: A plasmid is a small DNA molecule that's separated from a chromosomal DNA and can replicate on its own.  Restriction mapping is obtaining the structural information of DNA by using restriction enzymes. These restriction enzymes cut DNA at specified regions called "sites". 

Methods: We started out by adding the dye into each designated slot of our gel. We were to aim the pipet into the groove without puncturing the gel. If we punctured the gel or placed the gel in the opposite way, this would have ruined our experiment. After adding the dye to each slot, we let it sit for a day so the restriction enzymes could cut at their specified region. The next day, we came back and measured how far each DNA region traveled down the gel. 


Data

Graphs and charts

Discussion 
    Our results from this lab came out to be very close to what they should have been.  The only aspect of our results that did not come out ideally is the number of cuts that were made in the final two columns.  While there should have been three distinct cuts in the fifth column, and four in the sixth.  Our gels only showed two cuts in the fifth column and three in the sixth.  A potential reason for this outcome may be that we simply could not see the cuts due to a lack of pigment in the gel.  This pigmentation issue was probably derived from the beginning of the experiment when the liquids were being placed in the gels.  If any amount of the contents from the reaction tubes escaped during the piper ting process, it would make the fragments more difficult to detect.  This means that when loading the last two wells, a large amount of the liquid escaped, and therefore we could not see the extra fragments.  In the future, we would be more careful and precise when transferring the fluid from the reaction tubes to the wells. When labeling our fragments based on size, we knew that the larger fragments didn't travel very far, versus the smaller fragments, which went the largest distance.  With this in mind, we made general estimations on our own gel.  In doing this, it is possible that the lengths we assigned to our fragments may be off.  However, when considering the data, it is all compared to each other, so there should not be much wrong with what information we came out with in the end.  All in all, this was a successful experiment.


Conclusion
To conclude our lab, restriction map information is important for many processes used to manipulate DNA. In this lab for example, one application was to cut a large strand of DNA into smaller pieces to allow it to be sequenced. We were successfully able to characterize a DNA sequence through this process. 

Gel map artfully drawn out by Mr.Filipek (super artistic and well-done)
Emma adding the DNA loading dye to our gel (super successful)
Our whole classes gels all together in the electrophoresis chamber (most of them look amazing good job class)
Our lab group's gel after the electrophoresis was complete