Key Enzymes and Concepts in DNA Replication

DNA polymerase

An enzyme that catalyzes the formation of phosphodiester linkages between deoxyribonucleotides, forming the primary structure of DNA.

DNA ligase

An enzyme that catalyzes the formation of phosphodiester linkages in gaps between two existing nucleotides in double-stranded DNA.

Origin of replication

A location (a point) where enzymes open the DNA double helix so replication can begin.

Replication fork

The y-shaped structure visible in micrographs of DNA during replication. This is the site where the replisome works, synthesizing the leading and lagging strands.

Primase

An enzyme that adds a short RNA primer to single-stranded DNA, so DNA polymerase can start adding complementary bases.

Replisome

The multi-molecular machine that works at the replication fork, copying DNA.

Helicase

An enzyme in the replisome that opens the DNA double helix, creating single-stranded template DNA that become the leading and lagging strand during synthesis.

Topoisomerase

An enzyme that is important in DNA replication. It breaks and rejoins DNA to relieve the tension created when helicase continuously opens the double helix.