The genetic information embodied
in DNA can be replicated into more DNA. When DNA is replicated, its two
strands are split and each strand serves as a template for a new forming strand:
Each base in the template dictates the complementary base in the new strand.
The replication reaction is catalyzed by the enzyme DNA polymerase. This
enzyme can extend a chain, but cannot start a new one. Therefore, DNA synthesis
must first be initiated with a primer, a short oligonucleotide (nucleotide
chain). The oligonucleotide generates a segment of duplex DNA that is then turned
into a new strand by the replication process (see figure 1.1).
