How are DNA from hair follicle and skin cell used to determine if they belong to same person?

Answer 1

DNA can be extracted from tissue, in this case, epidermal layers of skin (keratin doesn't have nuclei) or the hair follicle. The DNA is then amplified using a process called polymerase chain reaction (PCR), to create many more copies of the DNA segments using special coding sequences called primers. The segments can then be digested with enzymes (restriction enzymes) to create DNA fragments. Differences in DNA sequences create different sized DNA fragments, which are then separated on a gel matrix using an electric current (electrophoresis). The pattern of different sized fragments is unique to an individual, somewhat like a bar code. Two similar fragment patterns are compared, and if similar suggest identity (RFLP - restriction fragment length polymorphisms). You increase the chances of proving identity between the hair and skin if many different restriction enzyme reactions are done showing similarity between many different fragment sizes.