DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus where it is called nuclear DNA, but a small amount of DNA can also be found in the mitochondria where it is called mitochondrial DNA or mtDNA. (U.S. National Library of Medicine, 2012)
Although DNA was discovered earlier, there still remains a lot to be known about it, especially how it is used to determine the physical traits that we all have, and how it regulates the workings of the body. DNA Extraction is the removal of deoxyribonucleic acid (DNA) from the cells or viruses in which it normally resides. Extraction of DNA is often an early step in many diagnostic processes used to detect bacteria and viruses in the environment as well as diagnosing disease and genetic disorders. (Rice, 2012)
A. Extracting DNA from Plants
In this part of the experiment, DNA was extracted from the cells of onions. A buffer solution was used in this experiment for several reasons. First the table salt, this was used so that the DNA will like to dissolve because of the saltiness and acidity (pH) of the solution. Second, detergent was used to help break down cell walls in the onion cells. Because detergent is used to break apart greasy particles in your clothes, it will also work to tear apart the “greasy” molecules in cell walls. Cell walls in living things are made of long polar molecules with a “greasy” end and a charged end. It is important to break the cell walls because the DNA is inside the cell.
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was the first naturally-occurring antibiotic discovered - and the first to be used therapeutically. An antibiotic is any substance produced by a microorganism which can kill or inhibit the growth of a different microorganism. We now call such substances, and any similarly-acting substances which humans design, chemotherapeutic agents. Before we begin to talk specifically about penicillin, it will ...
To slow down the rate at which the DNA breaks up, we cool down the buffer solution to near freezing, that is why the buffer solution was needed to put in an ice bath. As important as DNA molecules are to life, they are still fragile, and break apart easily when removed from cells. Chemical reactions always take place slower in cold solutions than in warm ones, because there is a lot less energy around to make the reaction take place.
Figure 1. Mashing the pieces of onion using blender
Figure 1 shows the mashing up of onion using blender. Onion was needed to be mashed to be able to break the cell walls releasing the DNA into the juice or at the very least expose the cell walls so the detergent can break them down. The onion was exposed to the detergent solution so that it will be able to break up the cell walls, releasing the onion DNA into buffer solution.
Figure 2. Filtering the Onion juice
After filtering, the expected clear solution must have consisting dissolved DNA fragments, as well as some other biochemical compounds such as RNA and some proteins. DNA is a very long molecule, but compared holes in a piece of filter paper, the molecule is still small enough to pass through.
Figure 3. The extracted DNA from plant (onion)
After adding a cold alcohol, figure above shows how the extracted DNA looks like. The cold alcohol is used to extract the DNA from the onion juice. The reason why the alcohol must stay on top of the onion juice is because by doing that the liquid will form two distinct layer. Generally, molecules are attracted to the boundaries of two liquids. The concentration of large molecules can be much higher at the boundary between two liquids. (Extraction of DNA from an Onion, 1999)
B. Extracting Human DNA
In this experiment saliva was used in extracting DNA. To protect the DNA, several steps were conducted because enzymes that degrade DNA are actually found in saliva and skin. Saliva is just one of the methods used to extract DNA. Others used blood, skin from the mouth, hair, nails, and more. Saliva was used as an alternative source of DNA for known standards. And it can actually be collected in a non-invasive manner without any pain. Generally, fresh whole blood is the primary source of an individual’s DNA which is used as a standard for comparison to evidentiary material in DNA typing. Salivary DNA is equivalent in quantity and purity to DNA obtained from blood and that the stability of DNA is good when proper methods of handling are employed. (Collecting and Handling Saliva for DNA Analysis, 2009).
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*To make the extraction buffer, 100 ml of shampoo (without conditioner) was mixed with 15 g of NaCl and 900 ml of water. Procedures Used in Experiment Once all materials were gathered by group members, each individual group began their experiment. The first step was to place the strawberry or banana in the zip lock bag and smash the strawberry/banana for 2 minutes. The strawberry produced enough ...
Figure 4. The extracted Figure 5. Extracted Human DNA human DNA (Saliva) (saliva) spooled with the wooden sticks.
One of the members of the group collected enough saliva to fill a test tube to about one inch of its length. This possibly, in order to insure that sufficient amounts of DNA could actually be extracted. In the image above, Figure 4 shows the extracted human DNA using saliva. This was look like after adding full cold ethanol and was gently mixed. The next image, which is Figure 5 shows what is look like when the DNA was spooled with the wooden sticks.
Saliva may contain nasal bronchial debris, tears, blood from micro injuries in the mouth, serum, exudates from the gums, and the food and cellular debris. It is actually a mixture of the secretions from all of the various salivary glands located in the mouth.
DNA from saliva originates from cells that are shed from the inner linings of the mouth and from white blood cells. These DNA-containing cells are collected, and the DNA is then extracted by various methods. (Collecting and Handling Saliva for DNA Analysis, 2009).
DNA is extracted from human cells for a variety of reasons. With a pure sample of DNA you can test a new born for a genetic disease, analyze forensic evidence, or study a gene involved in cancer. (Science Education Partnership Award, 2012)
References
(1999).
Extraction of DNA from an Onion. Cavalcade Publishing. Rice, G. (2012, November 25).
DNA Extraction. Retrieved November 26, 2012, from Microbial Life Eduactional Resources: http://serc.carleton.edu/microbelife/research_methods/genomics/dnaext.html U.S. National Library of Medicine. (2012, November 19).
The Term Paper on Criminology DNA Forensic Science
We begin life as a single cell zygote, about 0. 1mm in diameter. The numerous biological instructions that enable our developmental and functional processes to occur from zygote to adult are encoded in the deoxyribonucleic acid (DNA). Forensic DNA analysis involves the intersection of several scientific disciplines, including molecular biology, genetics, and statistical analysis (Lynch, 2013). In ...
What is DNA? Retrieved November 23, 2012, from Reference, Genetic Home: http://ghr.nlm.nih.gov/handbook/basics/dna
Collecting and Handling Saliva for DNA Analysis. (2009, August 19).
Retrieved November 24, 2012, from Salimetrics: http://www.salimetrics.com
Science Education Partnership Award. (2012).
DNA Extraction Virtual Lab. Retrieved November 24, 2012, from www.dna_extraction_virtual_lab.com
