Introduction: Deoxyribonucleic acid or DNA is the building block for all life. Every living thing has DNA to store genetic information. It is responsible for determining many traits in a person, like hair, skin, and eye color. It also gives cells directions to perform all of the functions that are needed in an organism. The DNA structure is known as a double helix, because of the two spiraling strands that run anti parallel to each other. The two stands are held together by bases; the four bases are A (adenine), G (guanine, T (thymine), and C (cytosine). The bases are connected to a sugar and a phosphate group to form a nucleotide. Also, the base A always pairs with T, and G always pairs with C. These four bases are organized into your genetic material, and make messages for cells that are called genes. These genes code for the construction of proteins, which serve as the basic functioning unit for the body. In humans, our DNA sequence is 99.9% similar, and the .1% causes each individual to be unique. DNA is found within the nucleus of a cell. DNA wraps around proteins to form structures called chromosomes. Humans have 23 pairs of chromosomes, and the chromosomes make up all your genetic information in your genome. While DNA holds the directions for making proteins, the genes do not actually directly make proteins. Cells use ribonucleic acid or RNA to transfer parts of the DNA sequence to the ribosomes to make proteins.
Purpose: The purpose in this lab is to precipitate DNA.
Procedure: 1) Label tube with full name
2) Gently chew cheeks in order to loosen cheek cells
3) Rinse mouth with saline solution. The saline solution serves to neutralize the negatively charged DNA.
4) Spit solution back into tube
5) Add 2 ml of lysis buffer to break open and dissolve cell membrane; it dissolves the cell membrane by dissolving the phospholipids. The lysis buffer acts in a similar manner as dish soap and detergent.
6) Gently invert tube 5 times
7) Add 100 ml of protease, which is an enzyme that breaks down proteins. The specific protein we are looking to destroy is DNase, which breaks down DNA.
8) Gently invert tube 5 times
9) Place tube in water bath at 50 *C for 10 minutes to speed up the reaction and help break open the cell membrane.
10) Pour 10 ml of cold alcohol into tube, this action starts to precipitate the DNA.
11) Let tube sit for 5 minutes
12) Invert tube 5 times
13) Transfer DNA into necklace
Results and Observations: The DNA was formed inside the tube. The DNA never precipitated until I added the cold alcohol.
Discussion: The lab worked very well for me. I got a good amount of DNA to precipitate. Adding the lysis buffer and protease allowed me to get access to the DNA, and then protect the DNA from DNase. Then, the cold alcohol served to precipitate the DNA out of solution. Some possible sources of error in this lab could have been not getting enough cheek cells. If you shake the DNA solution to hard, it could cause the DNA to go back into solution.
Excellent - A+
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