Origin

Definition

The origin is the specific location on a chromosome where DNA replication begins. In prokaryotic cells, this site is called the origin of replication or oriC.

5 Must Know Facts For Your Next Test

1. The origin of replication in prokaryotes is typically a single, fixed site on the circular chromosome.
2. In E. coli, the origin of replication is known as oriC and contains multiple AT-rich sequences.
3. Initiation of DNA replication at the origin involves several proteins, including DnaA which binds to DnaA boxes within oriC.
4. The helicase enzyme unwinds the DNA at the origin to allow replication forks to form and progress bidirectionally.
5. Mutations in the origin region can severely disrupt the ability of a cell to replicate its DNA properly.

Review Questions

Related terms

Replication Forks: Structures that form at the origin and move along the DNA as it replicates

DnaA Boxes: Specific sequences within oriC where DnaA proteins bind to initiate DNA replication

Helicase: An enzyme that unwinds double-stranded DNA at the replication fork