The Rosetta Stone: Slide Show
The DNA Molecule
The DNA molecule is a double helix. The two strands are bound together by base pairs. Each base pair is a linkage between two nucleotides. There are four different nucleotides in DNA, labeled G, C, T, and A (guanine, cytosine, thymine, or adenine). Because of their structure, A only bonds with T, and G only bonds with C. This means that a single strand of DNA is sufficient to build another strand -- a mirror image of the original. The sequence of letters determines which proteins a gene (a small subsegment of the DNA) builds.