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THE NATURE OF DNA

المؤلف:  Max M. Houck، Jay A. Siegel

المصدر:  Fundamentals of Forensic Science

الجزء والصفحة:  p263-264

2026-08-13

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THE NATURE OF DNA

Deoxyribonucleic acid (DNA) is a complex molecule found in nearly all cells in all animals and plants. Notable exceptions in humans include red blood cells that have no nucleus. DNA is a special type of molecule known as a polymer, a molecule made up of repeating simpler units, called monomers. DNA is located in two regions in a cell, the nucleus and mitochondria. Both can be used in DNA typing; however, mitochondrial DNA (mtDNA) is of a different length and shape and is used differently than nuclear DNA in the characterization of biologic evidence. Unlike nuclear DNA, it is inherited only from the mother. mtDNA will be covered later in this chapter.

FIGURE 1 The DNA double helix. The backbone of the DNA polymer is made up of sugar molecule (deoxyribose) and phosphate. The bases bind in pairs. Only C and G can bind with each other and only T and A can bind with each other. There are more than 3 billion base pairs in the human genome.