DNA PROFILING
DNA PROFILING
The process of DNA Profiling was invented by Alec Jeffrey's (who is a British geneticist) at the University of Leicester. He was knighted in 1994 for his contribution.
DNA Profiling is a technique used by forensic scientists to distinguish between individuals of the same species using only samples of their DNA. It is a powerful tool in criminal investigations. Its success in the courtroom depends on many factors, including:
◾Proper handling of evidence.
◾Careful analysis by an unbiased forensic laboratory.
◾Fair and appropriate interpretation of the results by forensic investigators.
◾Accurate and effective reporting of results to judges and jurors.
When used correctly, DNA evidence can quickly eliminate a suspect. It can provide compelling evidence to support a conviction and most importantly, reduce the chances of a wrongful conviction.
Stages of DNA Profiling:
Stage 1: Cells are broken down to release DNA. If only a small amount of DNA is available, it can be amplified using the Polymerase Chain Reaction (PCR).
Stage 2: The DNA is cut into fragments using restriction enzymes.
Stage 3: Fragments are separated on the basis of size using a process called Gel Electrophoresis.
Stage 4: The pattern of fragment distribution is then analysed. Use a sheet of nitrocellulose or nylon to blot the DNA. The sheet is stained so the different lengths of DNA bands are visible to the naked eye. By treating the sheet with radiation, an autoradiograph is created. This is an image on x-ray film left by the decay pattern of the radiation. The autoradiograph, with its distinctive dark-colored parallel bands, is the DNA profile.
◾Proper handling of evidence.
◾Careful analysis by an unbiased forensic laboratory.
◾Fair and appropriate interpretation of the results by forensic investigators.
◾Accurate and effective reporting of results to judges and jurors.
When used correctly, DNA evidence can quickly eliminate a suspect. It can provide compelling evidence to support a conviction and most importantly, reduce the chances of a wrongful conviction.
Stages of DNA Profiling:
Stage 1: Cells are broken down to release DNA. If only a small amount of DNA is available, it can be amplified using the Polymerase Chain Reaction (PCR).
Stage 2: The DNA is cut into fragments using restriction enzymes.
Stage 3: Fragments are separated on the basis of size using a process called Gel Electrophoresis.
Stage 4: The pattern of fragment distribution is then analysed. Use a sheet of nitrocellulose or nylon to blot the DNA. The sheet is stained so the different lengths of DNA bands are visible to the naked eye. By treating the sheet with radiation, an autoradiograph is created. This is an image on x-ray film left by the decay pattern of the radiation. The autoradiograph, with its distinctive dark-colored parallel bands, is the DNA profile.
Crime: Forensic Science is the use of scientific knowledge in legal situations. The DNA Profiling of each individual is highly specific. The chances of two people having the same DNA is 1/30,000 million (except for identical twins). DNA Fingerprinting can be used to solve crime scenes (Blood, semen, skin, hair or other body tissue cells, which are left at the scene of a crime can be analyzed to help prove whether the suspect was or was not present at the crime scene.). It can also be used to identify a body. This is very useful if the body is unrecognisable or if only body parts are available.