DNA extraction is a procedure of isolating the DNA from other cellular components for the molecular or forensic analysis. Usually a machine is used to extract DNA from the cell that is called as Bead Beater. It breaks the cell and extracts the DNA from it. Gel Box is another machine which separates the sequences of DNA in the gel. An electric current is used for this purpose. In the end, centrifugation separates the DNA from the solution through spinning.
Purpose of DNA Extraction:-
Extraction of DNA is an important step in the diagnosis use. It is also useful for the detection of bacteria and viruses and from the environment and it also provides chance to diagnose diseases and other genetic disorders which cannot be identified through any other means. There are some techniques which are important for the extraction and analysis of DNA for example, T-RFLP is helpful in identifying, characterizing and quantifying temporal patterns in marine bacterioplankton communities. Similarly FISH is another technique which is used to identify special groups of bacteria.
Following steps are involved in the procedure;
1) First the cell of interest is taken which contains the desired DNA. It is either taken from an animal or virus.
2) By using bead beater, cell is degraded and opened. For this purpose phenol often proves helpful in breaking the cellular walls which are made up of proteins or the capsule of viruses.
3) If a detergent is added to the solution, it will be helpful in removing the lipid layers.
4) An enzyme Protease is used to degrade all kinds of proteins whether they are associated with DNA or present inside the cell. Proteins are precipitated by the ammonium or sodium acetate salts. After this, proteins are ebbed by the phenol chloroform and centrifuged. Due to this process, the proteins will stay in the organic form and will be taken out of the solution with care.
5) After the removal of proteins, DNA molecules will be present at the interface.
6) Then precipitation of DNA starts to isolate it. Cold ethanol is used for this purpose. After precipitation, it is centrifuged.
7) As DNA is an insoluble in alcohol that is why it will come out of the solution immediately. Alcohol also helps to remove salts which were added in the beginning of the procedure.
8) Extracted DNA is washed again with alcohol to centrifuge it. DNA then will be suspended again in the buffer solution like TE or Tris.
9) To make sure that DNA is fully extracted, electrophoresis is done on an Agarose gel. Ethidium bromide is present in that gel which acts as a fluorescent dye. It will react with the DNA and will make the DNA visible under ultraviolet light.
Importance of DNA extraction in Forensics:-
DNA extraction is important in many ways. The extracted DNA can be used for genetic testing. Genetic testing is a technique used for the identification of the criminals. Sometimes it happens that no evidence can be obtained from the crime scene only a small piece of nail or hair, for that reason, only DNA can only five the identification about the criminal. If there is a case of child paternity then also it helps a lot.
DNA extraction is also useful in the identification of the victims of 9/11 incident. It has also played an important role in the identification of the people who were murdered and kidnapped in 1970s Argentina.
Major diseases like cancer can be cured by identifying the defected genes on the DNA molecule and replacing them with the healthy ones by using the techniques of genetics. Other important feature of DNA extraction is to identify the origin of wine. It is done so by tracing the lineage of grapevines. It is also helpful in tracing species which are getting extinct these days.
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