Forensic DNA Analysis: Quantitation & Amplification

• DNA is life's blueprint, encoding genetic instructions for the development of all known living organisms and viruses.
• DNA is a double-stranded nucleic acid consisting of two long biopolymers made of nucleotides.
• Forensic DNA analysis is a multi-step process that begins with removing DNA from biological material.
• Biological materials used in forensic DNA analysis include saliva, blood, semen, hair, skin cells, or any biological material containing cells with a nucleus.
• DNA is extracted from the nucleus through a process where cells are broken open using chemicals and heat.
• After extraction, the materials undergo a cleanup process to obtain pure DNA.

Quantitation

• Quantitation is preformed to determine how much DNA was retrieved from the cells.
• Quantitation is important, as the next step requires a specific amount of DNA for optimum results.
• Too much or too little DNA requires concentration to be adjusted before the next step.

Amplification

• Amplification involves copying specific regions inside the DNA molecule.
• Fluorescent tags are placed on regions of the DNA molecule during amplification.
• These fluorescent tags will be used in the detection step.

Detection

• The detection process involves separating copied fragments of DNA by size and passing them through a laser.
• When the laser hits the fluorescent tags, a camera determines the tag's color and quantity.
• This process results in a DNA profile, which is a set of numbers at the different regions tested, called a Locus.
• One of the numbers at each Locus comes from the mother, and the other from the father.
• Current DNA testing gives results at 16 different areas.
• Results at all 16 areas is considered a full profile.
• If an individual's DNA profile matches a DNA profile from evidence at a crime scene at all 16 areas, they can be placed at the location by law enforcement.