Electrophoresis Lab Report
Abstract: Jenna
The Electrophoresis Lab was to test the theory that the shorter the fragments of DNA the further they are able to travel from a negative to positive charge. DNA naturally has a negative charge. An electrophoresis lab is a common technique used for separating DNA segments. The segments are separated based on their size and charge, which shows the purpose for using a power source in the lab.
Introduction/Background Information: Kyle
DNA is negatively charged, and as such can be stimulated by electricity to be pulled through gel. This test is used to determine the size of molecules, as small DNA will move more quickly through the gel than large DNA molecules, due to the resistance from the gel. These groups of DNA are cut into smaller fragments using a restriction enzyme, which can cut the DNA at the end of a codon. Fragment size is usually reported in “base pairs,” which is the # of pairs which create the DNA helix. Three pairs creates a codon. The four types of molecules that make up DNA can only match to a certain other type. This combination creates almost words, which code for the DNA, which the DNA uses to determine traits. The more base pairs, the more codons there are in the DNA fragment, which in turn means the DNA is coding for more. All this will determine the speed at which the DNA moves through the gel.
Method/Procedure: Lauren
This study was completed at New Tech High @ Coppell over the course of five days. To start the lab, we got out a gel casting tray, which we sealed the edges and put a comb in. We poured in the agarose gel and carefully removed any bubbles we saw. The agarose gel then solidified after we waited 20 minutes. After the agarose gel set, we removed the seal and placed the tray near the black cathode. The box was filled with buffer until the surface was completely coated. Next, we gently removed the comb and made sure the holes left by the comb were completely submerged. We loaded the holes with contents from the pipet. Next, we closed the top of the electrophoresis chamber and turned it on. We turned off the power and examined the tray.
Results/Data: Kyle
Our results on our own gel did not turn out visible. Instead, we used the test results provided by Mrs. Wootton. These results show that the more base pairs a DNA fragment contained, the further the negatively charged DNA fragment was pulled by the electric field through the gel towards the positive end.
The below graph shows the relationship between distance traveled, and base pairs of a DNA fragment. It also contains a line of best fit.
Discussion: Jenna
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The separation of the larger DNA segments from the smaller DNA segments is easily seen in the 0.8% gel. The limitations of the gel aren’t seen and the smaller DNA segments are able to separate slowly but slightly easier from the larger fragments. Small DNA fragments are able to travel faster allowing them to separate easily from the larger fragments. The 0.8% gel is able to separate smaller fragments easier than large fragments.
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Lower bp DNA levels can be separated by a lower percentage of gel. Previously seen, the 0.8% is able to separate larger than 21,000 bp samples and to separate smaller levels requires a lower percentage in the gel.
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To separate 1,000 bp, 500 bp, and 100 bp DNA samples then a 0.1%-0.3% should be able to separate the DNA fragments.
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Once the DNA samples are inside the individual pockets on the negative side of the casting tray then place enough buffer to cover the surface of the gel and place inside a baggie. Place the baggie inside the fridge to freeze to keep the DNA fragments in place.
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In order for the lab to produce results you have to place the casting tray correctly into the box that you’ll receive the power source from. The DNA samples were place on the negative strips. For the charge to travel correctly the negative side of casting tray has to match up to the negative side of the power source. When the generator is powered on the DNA will want to travel to the positive side. If the sides don’t match up the DNA sample will travel in the opposite direction than desired.
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A restriction enzyme has the property of cleaving DNA at or near a certain sequences of bases in the DNA code.
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The use of restriction enzymes will show which DNA sequences are cut by the enzyme. If it is known what base sequences are cut then you can determine the sequences that were in the original DNA strand thus label it properly.
Conclusion: Lauren
Electrophoresis is a process in which molecules can be separated. It is caused by a presence of charged interface between the surface of a particle and the surrounding liquid. This technique applies a negative charge, which causes proteins to move towards a positive charge, leaving DNA behind. This is how electrophoresis works. Restriction fragment length polymorphism is a technique that exploits DNA locations using restriction enzyme sites. A restriction enzyme is an enzyme that cuts DNA. Ligase is an enzyme that joins two molecules together by using a chemical bond. We learned a lot in this lab about DNA and enzymes.
Citations:
http://biotechlearn.org.nz/themes/dna_lab/gel_electrophoresis