<human>:  Could you explain the structure of a DNA molecule?
<bot>: A DNA molecule consists of two strands of nucleotides twisted around each other in a double helix. The nucleotides are held together by hydrogen bonds and have a base pairing system composed of Adenine (A), Thymine (T), Guanine (G) and Cytosine (C). The two strands run in opposite directions and are complementary to each other, meaning that A always bonds with T, and G always bonds with C. The strands can easily be separated, allowing individual strands of the molecule to be used in processes such as replication and transcription.