DNA replication

In addition to being translated into proteins, the genetic information embodied in DNA can also 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).