What is the genetic material of living things? How to easily isolate DNA from human cells? What is the importance of being able to extract DNA?
If you are interested in these questions, welcome to my blog!
My name is Ayaulym Chamoieva, and I am a SST (School of Science and Technology) student at Nazarbayev Univesity. As I am a Biology major student, I am interested in biological sciences. Particularly, this blog will focus on DNA extraction and describe how to isolate DNA from human cheek cells.
Life depends on the ability of living cells to compactly store and translate genetic materials. These materials have the stable storage within every cell in its genes, which are the elements containing information about the characteristics of living species.
According to the Alberts. B., Bray.D., Hopkins.K., Lewis.L.. Essential Cell Biology. 2010, Deoxyribonucleic acid (DNA) is a carrier of genetic information present in all living things. It is required for all cells to perform vital functions. DNA is located in the nucleus of the cell. It is estimated that the human body contains approximately 50 trillion cells; all of the cells contain the same DNA.
The most interesting factor is DNA is responsible for everything that makes a human individual. For instance, it determines a person’s hair, eye color, facial form, height, blood type and etc. Genetic information is inherited; it passes from one generation to another. In fact, every person has own blueprint which is a joining of half of the mother’s DNA and another half of the father’s.
At the molecular level, DNA has a double helix structure, it looks like a spiral ladder made by two strands that consisted of linear sequence of nucleotides(Adenine, Cytosine, Timin, Guanine and Uracil) – monomers of DNA molecule.
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| Image 1 |
Turning to the isolation of DNA, there are several types of DNA extraction procedures, such as from hair, onion cells, kiwi cells, cheek cells and etc. The most commonly used procedure is DNA isolation from human cheek cells, which is clearly shown on Image 2. This is easy and convenient procedure to do in the laboratory. Firstly, gently chew the inside of your cheeks for 30 seconds. This will remove dead cheek cells. Then swish the 3 ml of water and expel obtained sample into 15 ml tube. Then add 2 ml of lysis buffer to the tube and accurately invert it several times. It helps to DNA release by destroying nuclei membranes of the cells. After this, add 50mL of proteinase K to the sample by using micro pipette and invert a few times. The role of proteinase is to catalyse the breakdown of unwanted proteins which are present in the solution. It is important to mix it vigorously to avoid breaking down DNA fragments. Test tube should be placed in water bath at 50oC for 20 minutes. Addition of 10 drops of salt solution (NaCl) helps to improve precipitation by giving ionic strenght. Then by adding 10ml of cold 95% ethanol solution to your tube DNA will precipitate out and store forming white precipitate layer. The sample should not be disturbed for about 5 minutes; otherwise DNA does not aggregate in the tube.
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| Image 2 |
Amazingly, we are able to see DNA from simple test tube. The reason is that length of DNA from one human cell (from 46 chromosomes) is about 2 meters long; however weigh is only 2 nanometres.
During the experiment on DNA purification, it can be concluded that isolation of DNA plays essential role in biology. The importance of DNA extraction is detection of viruses and bacteria, diagnose dangerous human diseases and prevent genetic disorders. In addition, nowadays DNA extraction is commonly used in the area of genetic engineering. Especially, it can help to increase productivity of new biological discoveries and develop the sphere of medicine.
References:
Bruce Alberts, Dennis Bray, Karen Hopkins, Julia Lewis. Essential Cell Biology. (New York: Garland Science, 2010)
