DNA Profiling By Derek and Blakely

What is DNA Profiling? DNA profiling also know as DNA fingerprinting is the process of using body tissues and fluids to identify a person or suspect in a crime or death. This process is widely used by the FBI and local police to identify an unknown person(s) that could have been part of a case.

DNA Profiling Steps The Genetic Evidence is obtained. The DNA is extracted. The DNA is amplified by PCR. Investigators cut the DNA in specific places determined by the use of restriction enzymes. The size and number of DNA fragments are visualized by using Gel Electrophoresis. The DNA evidence can be matched to a suspect’s DNA due to restriction fragment length polymorphisms(RFLPs).

Obtaining DNA Evidence At the scene of a death or crime, a Crime Scene Investigator will obtain the DNA and package it for use in the forensic labs. DNA can be obtained from hair, blood, skin, body fluids, and etc… The investigator must be careful for cross contamination.

Extraction of DNA The obtained DNA is then extracted by taking the genetic sample and breaking it down using a buffer to get the pure DNA extract. Then, the DNA is stretched into strands using ethanol to become visible.

PCR: Polymerase Chain Reaction Polymerase Chain Reaction is the process of amplifying the number of copies of a specific region of DNA. This allows for enough DNA to be adequately tested for later test. There are three main steps: denaturation, annealing, and extension. The PCR group will go further in depth. PCR song

PCR

Restriction Enzymes After the DNA is amplified, the specific regions are then cut based on a certain pattern using restriction enzymes.

Gel Electrophoresis After the DNA is cut, it is visualized using Gel Electrophoresis. The DNA is put in the wells of the gel and pulled down the gel using electric currents. This allow for us to observe the lipids or bands of DNA. These are the RFLPs or Restriction Fragment Length Polymorphisms.

RFLPs These Restriction Fragment Length Polymorphisms are comparable using the suspects and the crime scene’s DNA samples by the lipids or bands on the gels. Whiteboard examples

Conclusions With this information, Crime Scene Investigators can exonerate the suspects and find who or what exactly killed the victim!

Source Biology Corner, (nd.) Analyzing DNA Segments. [Accessed 16 September, 2014] Retrieved from http://www.biologycorner.com/APbiology/DNA/16_biotechnology_cloning.html. LSA,(nd.) The PCR Song and Lab Photos. [Accessed 16 September, 2014]. Retrieved from http://www.lifescienceacademy.net/documentation.html.