Analisi del DNA e probabilità

Abstract

DNA is a long molecule, which is the basis of the chemistry of living beings. The DNA of an individual is the cause of its uniqueness, whether it is a unicellular organism, a plant or an animal. Until about two decades ago the study of DNA was very difficult, but now PCR (polymerase chain reaction) generates in a short time specific sequences of DNA which initially are present only in a small quantity. The possible sources of DNA can be wide-ranging; consider that in simple contact, cells of our skin may separate in flakes containing DNA; from such samples PCR can read sequences of the DNA. Generally DNA analysis allows us to reach a percentage of attribution with an error of about 1/1012 (which means an error every 1000 billion analyses). Nevertheless, the extreme ease of leaving traces of DNA is the Achilles heel of biomolecular methods: if at a crime scene other people have passed, if the victim had contact with someone else before his death, if the objects have been touched by others in the past, different patterns of DNA will be found, which must, of course, be contextualized in order not to make serious errors of interpretation.