DNA profiles for forensic use
Each of the chromosomes in your cells contains sections of non-coding DNA — DNA that does not code for a protein. Non-coding DNA contains areas called short tandem repeats (STRs), made up of repeats of short base sequences, such as CATG in the sequence CATGCATGCATG.
If the DNA of two people was analysed for 10 different STRs on different chromosomes, there is only one chance in a million that they would have the same number of repeats in all of these STRs. Identical twins are the only exception — they have identical DNA and identical STRs.
If a crime suspect's DNA profile for 10 STRs matches the STR profile of a sample found at the crime scene, there is a very high probability that both lots of DNA are from the same person. However, if the profiles differ for even one STR, this cannot be assumed.
DNA is used as evidence in court, but it is considered ‘circumstantial' evidence, and can only be used as proof with other supporting evidence. However, it has proven useful in establishing the innocence of suspects.
If the DNA of two people was analysed for 10 different STRs on different chromosomes, there is only one chance in a million that they would have the same number of repeats in all of these STRs. Identical twins are the only exception — they have identical DNA and identical STRs.
If a crime suspect's DNA profile for 10 STRs matches the STR profile of a sample found at the crime scene, there is a very high probability that both lots of DNA are from the same person. However, if the profiles differ for even one STR, this cannot be assumed.
DNA is used as evidence in court, but it is considered ‘circumstantial' evidence, and can only be used as proof with other supporting evidence. However, it has proven useful in establishing the innocence of suspects.
No comments:
Post a Comment