CSI: AHS

Introduction

Background:
Current forensic study involving criminal activity is now heavily dependent on the practical use of DNA identification and comparison. It is important to rule out subjects who are innocent. Because they are all different people, so is the size of their DNA, thanks to restriction enzymes. These restriction enzymes act as molecular "scissors", that cut specific sequences of base pairs. Geneticists and criminal detectives both rely on this DNA sequence length to differentiate specific DNA from others that may be found. Developed by geneticist, Alec Jeffries in 1985, the practice of Restriction Fragment Length Polymorphism, or RFLP, has become the forefront for genetic profiling. The best application of this process can be found in agarose gel electrophoresis. Electrophoresis means to carry with electricity, which is key because DNA is negatively charged. When placed in the agarose gel, the DNA will travel toward the positively charged anode of the electric field. The speed in which specific DNA travels through to gel is inversely proportional to the size of the sequence of base pairs. After being stained, the template of the resultant DNA can be compared with the subjects that may have executed the crime. Since DNA is present in all cells of the human body, skin, blood, and other tissues can be used for comparison, making it easier to catch the culprit. Other uses include: food purification, identifying human remains, proving convicted inmates innocent, human relation to other species, ancestral relation, identifying lethal traits in organisms, paternity testing, etc.

Purpose:
The purpose for this lab is to have a better understanding of how DNA is fragmented, how DNA can be used for profiling and how to perform the process ourselves.

Procedure:

1. Place the restriction enzyme mix in ice
2. Label 6 tubes, first is CS, and the other 5 are S1 through S5. Give each an independent color, name, date, lab period. 
3. Take 10 microliters of the DNA of each suspect and place accordingly. Be sure to use a fresh tip every time
4. Add 10 microliters of enzyme to each and mix well. 
5. Close each tube and place them into the centrifuge
6. Incubate the tubes overnight
7. Pour 1% agarose gel
8. Refrigerate samples

Day 2:

1. Take samples from the refrigerator and put them into the centrifuge
2. Put 5 microliters of of loading dye into each tube and use the centrifuge once more
3. Take the agarose gel from the refrigerator and place it in the electrophoresis apparatus
4. Do a double check to see that the electrodes are touching the gel
5. Load the samples into 7 wells

They are designated in the following

• Lane 1- M, DNA size markers, 10 microliters
• Lane 2- CS, 20 microliters
• Lane 3-7- S1-S5 in order, 20 microliters each

Hypothesis

• Lizzie's eyes have been really shifty since day one. I'm afraid... I think she's the killer.

Due to a malfunctioning lab computer, our video was not loaded but shall be handled soon. I apologize for the wait.

Results:

After comparing the sets of DNA to the DNA in lane 2 from the crime scene, Lane 5 is the closest match to the crime scene DNA. That DNA belonged to Chloe (much to my surprise). Justice was pleased that day. 

Discussion:

This lab was awesome in the fact that it is more of a real world application than any other lab I have done in this class or previous classes. It intertwined the use of the class and proper technique for the pipets and the electrophoresis machine. I have a better understanding of how DNA is sorted based on the different lengths of the cut strands. More crime solving will be accurate if DNA becomes a standard for all organizations. Although I was gone for Thursday, It was still fun to guess the killer. Although Lizzie was innocent, I will be more cautious. 

Biofuels Lab

Introduction:
     In this lab, we will discover how to make biofuels. Biofuels are substitutions for the world's current fuel source, crude oil. Using the biomass of plants, scientists can synthesize cleaner fuel for the environment. By converting to biofuel, the plants that grow can clean the air of the carbon dioxide that is released from combustion. Granted that the harvesting of some products, like corn, for other than food, can create scarcity or market competition, the benefits outweigh the costs. If scientists genetically modify a plant that is specifically grown for this need, then competition will be less of a problem, and countries can more thoroughly fight crude oil dependency. After engineering said plant, scientists need to convert the biomass into usable fuel. In nature we have mushrooms that decompose material with their enzymes. These enzymes can be used for the genetically engineered plant to break down the cellulose and convert it into glucose. Through the process of microbial fermentation, ethanol can be harvested. The various types of fuel can be the new source of power in the future.
Purpose: Students, like us, become familiar with terms such as substrate, enzyme function, catalysts, and biofuels. Learning how enzymes are used to break down organic substances can be key for future in a career working in labs.
Procedure:
     Normally, the video would show the procedure of the lab, but since there are technical problems, i will summarize the significance of each step.

1. We will use a stop solution, an enzyme, and a buffer.
2. We will take 5 cuvettes to show the enzyme's product increase over time
3. Using the pipette, we put 2 ml of 1.5mM substrate into two conical tubes, one being the enzyme reaction and the other a control. 
4. We then took 500 microliters of buffer solution and mixed it with the control test tube.
5. Then we pipetted 1 ml of enzyme into the enzyme reaction tube.
6. After several intervals of time, we took 500 microliters of the enzyme reaction and put them in chronological order in the cuvettes.

Day 2 proved to be similar, except mushroom paste was added to increase the reaction rate of the reaction so that more products were made in less time. The natural enzymes in the mushroom used for decomposition represent the natural materials that can be used to create biofuels.

Results:
     The results were as predicted with the increased darkening over time of the yellowish color of each progressive sample of product. The mushroom extract in day 2 aided in the production times. We learned that the chemical reaction would not continue forever because eventually the production rate would plateau, due to  a lack of resources, therefore the reaction has limited reactants.

Conclusion:
     Overall, the lab gave a good review of chemical reactions and proper lab measurements. Biofuels are an important subject to teach early because future generations may not have the fossil fuel option that is currently being used. Nature presents a ready solution for an energy problem, so taking the opportunity for a clean, progressive movement is vital.