This session will explain how DNA is replicated prior to cell division. In this process, DNA polymerase uses an original strand as a template to create a new daughter strand of DNA. Polymerization occurs in the 5’ to 3’ direction, creating a new strand that is anti-parallel to the original. Polymerization begins at a specific DNA sequence called the Origin of Replication and proceeds in two directions along both template strands. Because of the directionality of synthesis, one strand is synthesized continuously, while the other strand is synthesized in small fragments, which are then joined together by DNA ligase.
Watch the lecture video excerpt
Below is a representation of an origin of replication and the two associated replication forks. Synthesis of new DNA occurs on both strands.
At Fork 1, which template strand (1 or 2) is copied in a continuous manner?
To which site or sites can the primer 5'-CAAGG-3' bind to initiate replication?
Help Session Video
Watch the short video of Sera Thornton explaining the numbering and labeling conventions of RNA and of proteins.
Suggested topics for further study in an introductory-level Biology textbook
- DNA Replication
- Replication: Mechanism of Replication (Basic), 3-D Animation Library
- Replication: Mechanism of Replication (Advanced), 3-D Animation Library