DNA, or deoxyribonucleic acid, is the molecule that carries the genetic instructions essential for life. Found in nearly all living organisms, it serves as the blueprint for building, maintaining, and reproducing cells. DNA is composed of two long strands that twist into a shape called a double helix. Each strand is made up of smaller units called nucleotides, which consist of a sugar molecule, a phosphate group, and one of four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and g...