The method shown in the picture above represents DNA fingerprinting.
- Also called DNA profiling, DNA testing, or DNA typing is a forensic technique used to identify individuals by characteristics of their DNA.
- It is used for paternity testing and forensic identification of suspects.
- A common method of collecting a reference sample is the use of a buccal swab.
- A sample of blood, saliva, semen, vaginal lubrication, or other appropriate fluid or tissue from personal items (e.g. a toothbrush, razor) or from stored samples (e.g. banked sperm or biopsy tissue) may be used.
- DNA fingerprinting can be done with all cells, except RBCs as they lack the DNA-containing nuclei found in all other cells.
- DNA profiling uses repetitive (“repeat”) sequences that are highly variable, called variable number tandem repeats (VNTRs), in particular short tandem repeats (STRs), also known as microsatellites, and minisatellites.
- One of the most common DNA fingerprinting procedures is RFLP: Restriction Fragment Length Polymorphism.
- Special enzymes are used to cut segments of a sample from which DNA is extracted.
- The procedure of RFLP focuses on repetitious sequences of DNA ‘bases’ which vary greatly from individual to individual.
- These segments are then separated using a technique called Electrophoresis, followed by comparison of the DNA fragment patterns among samples
- A more recent form of test is the STR Test (Short Tandem Repeat Test), which looks at DNA segments and counts the number of repeats at a number of different DNA sites – normally around thirteen.
- Polymerase Chain Reaction – another more recent test – can create multiple copies of the DNA sequence which helps to produce a usable DNA sample from a single human hair.