NORTH-WEST UNIVERSITY BGYM 314 GEL ELECTOPHORESIS Thage karabo 22300465 Brian Munansangu 22937803 Mohomud Adem 21888205 Phemelo Kampie 23129050 Thabang Mashila 23004622 Frankel Tabiso 23264748
Gel electrophoresis Gel electrophoresis is a procedure that separates charged molecules by migration in an electrical field. The rate of migration is determined by the charge on the molecule and by its size and shape. Gel is made of agarose or polyacrylamide, a polysaccharide. How gel electrophoresis works Firstly Deoxyribonucleic acid (DNA) has to be digested with restriction enzymes since it is usually super coiled. They cut DNA molecules into segments that range in length from a few hundred to a few thousand base pairs. After cleaving the DNA, the fragments generated can be separated from each other for this reason, DNA is usually cut with restriction enzymes prior to electrophoresis. Secondly a gel is prepared; The gel is prepared with wells at one end so that DNA samples can be loaded into the gel.
When nucleic acids are placed at the negative end of an electrical field, they migrate towards pole with a positive charge due to their negatively charged phosphate group. Each fragment’s migration rate is determined by its molecular weight so that the smaller a fragment is, the faster it moves through the gel. Migration rate is also a function of gel density. The presence of the gel meshwork hinders the progress of the DNA, and small or compact molecules migrate more rapidly than large molecules. The higher the concentration of the gel, the more large molecules are hindered. After the gel has been run for sufficient time to separate the DNA molecules, it can be stained with a compound that binds to DNA, such as ethidium bromide, and the DNA will then fluoresce orange under ultraviolet light. DNA fragments can be purified from gels and used for a variety of purposes.
Uses of Gel Electrophoresis Gel electrophoresis is used to provide genetic information in a wide range of data fields,Such as forensics, molecular biology, genetics, microbiology and biochemistry. Human DNA can be analyzed to provide evidence in criminal cases, to diagnose genetic diseases, and to solve paternity cases. Samples can be obtained from any DNA-containing tissue or body fluid, including cheek cells, blood, skin, hair, and semen. Separation of restricted genomic DNA prior to Southern transfer, or of RNA prior to Northern transfer.
ADVANTAGES Provides a clear link between similar results Relatively simple to perform Can test DNA from any type of evidence (hair, blood, skin, body fluidetc.) Relatively inexpensive
DISADVANTAGES The disadvantages of gel electrophoresis are: The gel can be altered and provide inaccurate results. User error can be catastrophic, depending on the mistake.
ETHICAL CONCERNS There are very few ethical concerns with gel electrophoresis, as it is only a process by which you can obtain DNA evidence, and is usually only used for the good of society, such as crime fighting, suspect identification, paternity testing, etc.
ReferencesWilly ,J.M & et’al.2008. PRESCOTT’S MICROBIOLOGY.Singapore: McGraw-HillMichael T. M & et’ al. 2012.BROCK BIOLOGY OF MICROORGANISMS 13TH ed.San Francisco: Pearson Education,inc.www.wikipedia.gel eletrophoresis.23 February 2013
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