DNA Precipitation Lab

Introduction:
    The genetic building block of all cells in the human body is deoxyribonucleic acid or DNA. DNA is composed of the deoxyribose sugar, a phosphorous group, the four bases adenine, cytosine, guanine, and thymine. The basic molecular components of cells, besides nucleic acid, are lipids, carbohydrates, and proteins.The cells themselves contain the entire set of DNA, but certain cells express different genes within the DNA. The expression of genes gives humans variation in their attributes, like body type, pigmentation, eye and hair color, etc. This D.N.A. is located in the nucleus, so many of the macromolecules stand in the way of retrieving said D.N.A. for observation.

Purpose:
    The lab teaches students how to precipitate DNA, which in normal terms means, more or less, solidify. Precipitating DNA allows studying the DNA and its traits, comparing other DNA, mapping it or sequencing the DNA, cloning, and testing for diseases.

Procedure Reasoning:
    First the student chews a little bit of the inside of their cheek to loosen the cells so the cells can be harvested for their DNA. The student then rinses out with a 0.9% saline solution which is an ideal salt concentration for the cells so the DNA does not break apart. Then the lysis buffer is added to break open the cell membrane, which is made of lipids. Lysis buffer breaks the membrane because the membrane is soluble in other other liquids besides water. Protease is then added, which is an enzyme that kills the enzyme DNAse. DNAse must be gone when the DNA is released because DNAse kills all DNA, due to the cell's evolution of its defense against foreign DNA. Adding table salt to the DNA solution shifts the proteins from hydrophillic to hydrophobic, which will break them away from the DNA in the nucleus. Placing the solution in a hot water bath denatures the protein, therefore speeding up the process. Finally adding the cold ethanol solidifies the DNA and it becomes much more visible than before.

Overall the lab was entertaining and we learned about DNA, some enzyme functions, and necklace assembly all in one.

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