ABSTRACT
Deoxyribonucleic acid (DNA) is found in cells. There are two types of DNA that can be typed using forensic methods—nuclear DNA (found in the nucleus) and mitochondrial DNA (mtDNA; found in the mitochondria). Aside from red blood cells, other cells in blood, skin cells, and cells found in other body fluids do have nuclear DNA. The DNA molecule found in chromosomes is the currency of genetics. Recall that DNA is a long double-stranded molecule that in the cell is found in a twisted ladder shape referred to as a double helix. Nuclear DNA is found on structures called chromosomes. Normally, humans have 23 pairs of chromosomes, including the gender chromosomes called the X and Y chromosomes. The characteristics that inherit from parents are encoded in regions of the chromosomes referred to as a gene. The base pair sequence in DNA is the order in which the bases are found on the DNA strand.
