Fig. 4. DNA Replication.

During replication the DNA molecule unwinds, with each single strand becoming a template for synthesis of a new, complementary strand. Each daughter molecule, consisting of one old and one new DNA strand, is an exact copy of the parent molecule. [Source: adapted from Mapping Our GenesThe Genome Projects: How Big, How Fast? U.S. Congress, Office of Technology Assessment, OTA- BA- 373 (Washington, D.C.: U.S. Government Printing Office, 1988).]