Forensic Biology and DNA Analysis – Blood, Semen, and Skeletal Remains Practice Exam

Decalcification with EDTA is the step that maximizes DNA recovery from bone because bone’s mineral matrix, mainly hydroxyapatite, traps DNA. EDTA chelates calcium and other divalent cations, dissolving the mineral matrix and freeing DNA so it becomes accessible to the lysis and purification steps. This not only increases the amount of DNA that can be recovered but also helps reduce nuclease activity by removing required cofactors, protecting the DNA during extraction. In contrast, using high temperatures can damage DNA and fragment it, avoiding decalcification keeps DNA locked in the mineral matrix and greatly lowers yield, and washing with water alone won’t remove the mineral or liberate the DNA.