Illustration of a DNA (deoxyribonucleic acid) molecule (helix) replicating. DNA is composed of two strands twisted into a double helix. Before replication, the strands separate from each other and each strand acts as a template. The enzyme DNA polymerase (red) synthesises a new complementary strand of DNA from each template strand to form two new DNA molecules (only one seen here). DNA contains sections called genes, which encode the body's genetic information.