DNA Fingerprinting

DNA contains genetic material and information that makes up each individual trait. Every person can be identified by providing his or her genetic information based on a particular DNA strand. DNA information is an effective way of identifying persons if it is used properly. It is used to identify humans in different situations such as crime scenes, accident scenes, paternity testing, soldier remain identification, inheritance claims, missing person investigations, and convicted felon databases. Although there are different ways to identify DNA, the most common method is DNA fingerprinting. The process that was used in the lab experiment was gel electrophoresis.

Before DNA fingerprinting, a different method called Blood typing was used. This method was used to identify people by taking a sample of dried blood. But this method had some disadvantages; for example, many people who receive blood by transfusionundergo changes in their blood characteristics, making difficult blood typing; also, blood typing required an amount of body fluid that sometimes was not enough or that other times deteriorated, making it impossible to do the blood typing. So, because of these disadvantages, DNA fingerprinting began to be used as a forensic tool.

Restriction Fragment Length Polymorphisms (RFPL’s) is a restriction enzyme that recognizes a specific strand of the nucleotides in DNA. This strand is different in every individual; the restriction enzymes cut the part of the DNA strand that is different, and it is used in gel electrophoresis to identify a person. For example, in crime scene investigations the DNA sample that is found is compared with the sample of suspects by the gel electrophoresis procedure in order to determine if the suspect committed a crime.

When doing the gel electrophoresis process, different DNA strands are set in the lanes of the gel, and they are run by an electrochemical gradient from negative to positive to separate these strands. When the strands separate, they group themselves in bands. The shortest bands travel at higher speeds; therefore, they are found at the end of the gel. This experiment gives the possibility to identify which bands are the same as the one that was found in the scene, allowing reaching the objective, which is to uncover who is responsible at the crime scene.

Materials

1. Restriction enzyme
2. Colored micro-tubes contain DNA samples
3. DNA loading dye
4. Agarose gel
5. Pipet
6. Tips
7. Electrophoresis apparatus
8. TAE Buffer
9. Centrifuge
10. 120 ml of 100X blue stain.
11. Tray
12. 40 to 50 Celsius of tap water.
13. Ice

Methods

1. In the lab experiment DNA samples were provided in colored micro-tubes that were incubated in ice.
2. 5 DNA loading dyes were placed in each sample tube and each tube was flipped gently with a finger.
3. A centrifuge was used to mix the DNA sample with the loading dye.
4. The agarose gel was placed on top of the gel to the negative side in the electrophoresis apparatus, and the electrophoresis box was filled with TAE buffer until it had completely covered the gel.
5. A pipet was used with different tips, and DNA samples were loaded into different lanes of the gel
6. The lid was placed in the electrophoresis chamber and plugged into the power supply.
7. The power supply was turned on and the samples were electrophoresed at 100V for 30 minutes. After that, the gel was removed carefully from the gel box and placed in a tray.
8. 120 ml of 100X fast blast of DNA stain was added. The gel was stained for two minutes with gentle movement.
9. The gel was transferred into a large tray and the gel was rinsed with warm tap water twice, with gentle shaking. The gel was left to dry for 24 hours.

Loading dye was Centrifuge was used Gel was placed DNA samples were placed in each to mix DNA and electrophoresis loaded in the gel micro-tube samples loading dye apparatus. Electrophoresis Gel was placed in aGel was transferred Gel was rinsed until the chamber was connected tray filled with to a clean tray the excess of stain to the power supply stain with warm tap water was removed

DNA Bands Data Table

Based on the results of the gel electrophoresis, suspect number three’s DNA sample matches the crime scene sample, not only because they look the same, but also because of the distance that strands travel along the gel, and the base pairs that they contain. The DNA bands of the crime scene sample were found at 10, 12, and 19 mm, instead of the bands of suspect numbers one, two, four, and five, which were found at different distances than the crime scene sample. Only the bands that correspond to suspect number three were found at similar distances to a crime scene one. Finally, the base pairs of the DNA bands of suspect number three and of the one found in the crime scene were 5,700 bp for the first set of DNA bands, 5,000 bp for the second set, and 2,250 before the third set. All of these results indicate that suspect number three was responsible for the crime committed at the crime scene.

Discussion and conclusions

In conclusion, DNA fingerprinting and electrophoresis were used to determine the size of the unique strand cut by restriction enzymes that identify the individual who was responsible at the crime scene. This lab taught me how to conduct an electrophoresis experiment, and how important the use of this method is to solve a problem that is common in society. In this process, different DNA samples were provided, and after doing the electrophoresis experiment, it was found that the suspect committed the crime. DNA profiling, which was called at first DNA fingerprinting, is used for other purposes, as was mentioned earlier. One of those is paternity testing.

At this time, this method has become less difficult than people may believe. Some laboratories provide this service, sending their clients a kit with everything that is needed to collect a sample of DNA. This sample, which could be a small portion of cheek tissue taken with a swab and put in a labeled envelope, is returned to the lab to be analyzed. Sometimes when this type of test is required for legal reasons, the sample to be evaluated taken under supervision order to avoid any intentional errors. DNA fingerprinting and profiling have become common processes, but also these have become very important because they help to get accurate results by using genetic information in order to solve different situations such as a crime or paternity identification.

Cite this Page

DNA Fingerprinting. (2016, Aug 08). Retrieved from https://phdessay.com/dna-fingerprinting/

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