This process is called elongation. Three of the four nitrogenous bases that make up RNA — adenine (A), cytosine (C), and guanine (G) — are also found in DNA. In RNA, however, a base called ...

DNA is always synthesized in the 5'-to-3' direction ... initiation requires a primer, elongation is always in the 5'-to-3' direction, and replication is always continuous along the leading ...

which lets small pieces of primer DNA bind to either side of the region of interest; and elongation, where the enzyme DNA polymerase zips along the single strands starting at the primer to ...