When collecting evidence with DNA, investigators must be especially careful to not contaminate the evidence with their own. At a crime scene, investigators will look for everything that could possible contain DNA evidence, from bloodstains to bed sheets. Disposable collection tools are used so that each piece of evidence is handled with a clean tool. Evidence is kept in paper bags so that it can breathe and is kept cool and dry as it is transported to a lab.
At the lab, DNA evidence undergoes a four step process before it can be used as evidence in court. The first step is extraction. Enzymes are introduced to the piece of evidence to release the DNA from the nucleus's of the cells. The second step is amplification, also known as the polymerase chain reaction (PCR). Amplification is essentially making copies of a DNA sample so that multiple tests can be done to one sample. The third step is electrophoresis. Electrophoresis can be thought of as "sorting" the DNA by size. DNA is suspended in a gel and an electric current is introduced. DNA molecules migrate through the gel as they are attracted to one end oar the other of the gel. The final step in DNA processing is analysis. Here, DNA processed DNA samples are compared; investigators look for patterns in the bands of the DNA.
At the lab, DNA evidence undergoes a four step process before it can be used as evidence in court. The first step is extraction. Enzymes are introduced to the piece of evidence to release the DNA from the nucleus's of the cells. The second step is amplification, also known as the polymerase chain reaction (PCR). Amplification is essentially making copies of a DNA sample so that multiple tests can be done to one sample. The third step is electrophoresis. Electrophoresis can be thought of as "sorting" the DNA by size. DNA is suspended in a gel and an electric current is introduced. DNA molecules migrate through the gel as they are attracted to one end oar the other of the gel. The final step in DNA processing is analysis. Here, DNA processed DNA samples are compared; investigators look for patterns in the bands of the DNA.