Crime Scene Investigation

The field of DNA profiling is relatively new, however, it is already being applied with great success by law enforcement. Using restriction enzymes to "cut" the DNA at certain points different sized strands of DNA are produced. This is called Restriction Fragment Length Polymorphism. Restriction enzymes are a naturally occurring bacterial defense system. They destroy invasive DNA by cutting it into small parts that will be harmless to the host. Using this technique allows the strands to be separated. Once separated the nucleotide sequence will be checked for similarities to suspects DNA nucleotide sequences. Any biological material that is found at a crime scene can be tested in this fashion and compared to suspects DNA in an attempt to solve a crime. Once the strands are separated they are placed on an agarose gel and electrified. The DNA has a negative charge so it will move towards the positive pole of the gel. The DNA can then be checked against suspects DNA to determine the perpetrator.

First, we removed the DNA samples and placed them in a centrifuge. Then we added 5 microliters of loading dye, which makes the DNA and also makes the sample heavier. Then we loaded the DNA samples into the wells in the agarose gel. Then we turned on the power to separate the samples with electricity. Then we waited 2 days and then placed the gel on a white box to examine the samples.

We concluded that suspect 3, Chloe, was the murderer. We saw that the DNA marks in her track matched the ones of the DNA that was found at the crime scene. These markings were fairly straightforward and easy to read. However, we could have possibly contaminated samples by using the same pipette tip or placing DNA in the wrong well.

Biofuel

Lately, people are trying to develop more environmentally friendly fuels. Biofuels are fuels made out of organisms that have been genetically modified. We are performing a lab that will test the effectiveness of a certain biofuel. We are testing it by adding it to a strong base at various increments of time. The strong base will react with it and cause it to turn yellow, so, the more yellow the beaker the more energy is in that beaker. Depending on how long it takes to become a dark yellow we will know how effective this biofuel really is. Also on the second day, we will grind up a mushroom, a decomposer, and add it to the solution. This should speed up the reaction time because of its enzymes. Our group predicted that the amount of glucose in solution will increase until a certain point when the reaction will run out of reactants and stop.

Breaking down cellulose is fairly simple as demonstrated in these steps: First we add cellobiase to the cellulose which breaks apart the cellobiose that is made up of 2 glucose molecules. The 2 glucose molecules can then be used as fuel. We will be testing how efficient this reaction is. We will do this by adding .5 mL of the created solution to .5 Ml of p-nitrophenol which will stop the reaction and change the glucose to a yellow color allowing us to easily determine how much glucose has been produced.

The results of the reaction appear to prove our hypothesis. The solution appeared darker in the 2 minute tube than it was in the 1 minute tube. However, after that the increase in color was miniscule if there was any at all. This could be for two reasons, either we didn't add enough p-nitrophenol or the reaction had actually slowed to an almost complete stop.