Final answer:
The ORC (Origin Recognition Complex) in eukaryotes binds to origins of replication, such as ARS in yeast, initiating DNA replication. This process is crucial for genome duplication, and ATP hydrolysis is necessary for the helicase to unwind DNA for replication to proceed.
Step-by-step explanation:
- The recognition of the replicator by the eukaryotic initiator, ORC, bound to ATP, is a crucial step in the initiation of DNA replication. In eukaryotes, the Origin Recognition Complex (ORC) specifically binds to sequences known as origins of replication. These sequences are areas in the genome where replication begins. In yeast, a eukaryote model organism, these sequences are referred to as Autonomously Replicating Sequences (ARS) and are critical for the proper initiation and regulation of replication. The ORC recognizes and binds to the ARS, initiating the formation of a pre-replication complex by recruiting other factors to the origin. The process is ATP-dependent, indicating that ATP hydrolysis is necessary for the helicase activity that unwinds the DNA to create a replication fork. Once the replication fork is established, enzymes such as DNA polymerases can begin synthesizing new strands of DNA.
In contrast to prokaryotes, which typically have a single origin of replication, eukaryotic chromosomes can have multiple origins to allow the genome to be replicated efficiently. The presence of these multiple origins is crucial due to the larger and more complex genomes of eukaryotes, which also replicate at a much slower rate of approximately 100 nucleotides per second.