Biology Lab Report
\Analyze and Interpret
A number of steps are required to isolate DNA from cellular contents. Describe what happens at each step, and why it acts to separate the parts of the cell. /6
There are three specific steps required to isolate DNA from its cellular contents. The steps used to remove and expose DNA from its cell are: breaking down the food type you are using by crushing it, for example a banana or strawberries, exposing the substance to a sodium chloride (NaCl) solution, subjecting the product to detergent solution (dH2O), filtering the solution and lastly, the addition of ethanol. When beginning with a solid substance, such as a banana, crushing the substance allows for breaking down the cell membrane and cell wall, if using a plant cell. This ultimately, removes the contents of the cell from the deoxyribonucleic acid (DNA) and further exposes it for the detergent solution. After this step, one would use NaCl solution to stabilize the DNA, since we know that it is negatively charged, due to the phosphate functional group. The way this occurs is when NaCl is added to the solution the molecule dissolves and forms ions. As a result, the positively charged ions neutralize the negative charge on the DNA molecule ("Discovering DNA" 20 Feb. 2014). The technique used to separate the DNA is by adding a detergent liquid to the solution, which allows for the cell membrane to break down. This step specifically emulsifies the phospholipids and proteins that make up the cell membrane ("Discovering DNA" 20 Feb. 2014), in order to further expose the DNA. Then in order to separate the DNA from the proteins and lipids one must use a filter paper with an appropriate pore size so that the flow rate of the solution is effective. Once the flow rate is minimal, the excess in the filter, consisting of cell debris and banana residue, can be disposed and then the filtrate is focused upon. With the specific amount of
Cited: Carter-Edwards, Trent, et al. Biology 12. Canada: McGraw-Hill Ryerson Limited, 2011 "Ethanol Precipitation of DNA and RNA: How it works." Bitesize Bio. N.p., n.d. Web. 20 Feb. 2014. “Extracting DNA from Living Things.” Nuffield Foundation. N.p., 2011. Web. 20 Feb Josephs, Molly. “Finding the DNA in a Banana.” Scientific American. N.p., 2011. Web. 20 Feb “Wheat Germ DNA Extraction.” Virtual Lab Book 5th Edition. N.p., n.d. 2000. Web. 20 Feb