Final answer:
Licensing of replication origins occurs during the initiation phase of the cell cycle in eukaryotic cells, ensuring that DNA is replicated precisely in the S phase.
Step-by-step explanation:
Licensing of replication origins, which involves the recruitment of pre-replicative complexes to the replication origin, occurs during the initiation phase of the cell cycle. In eukaryotic cells, this process is part of a highly regulated mechanism to ensure that genetic material is copied accurately and precisely. The licensing ensures that each segment of the DNA is replicated once and only once during the S phase.
In prokaryotic cells, such as E. coli, the process of DNA replication begins at a single origin of replication (oriC) and proceeds bidirectionally. However, in eukaryotes, there are multiple origins of replication on each chromosome, allowing replication to occur simultaneously from several locations in the genome, thereby ensuring complete replication during the S phase.
DNA replication in eukaryotes is a complex process that happens in three main stages: initiation, elongation, and termination. The initiation stage includes the binding of specific proteins to the origins of replication and the unwinding of the DNA helix by helicase to form replication forks.