Final answer:
Eukaryotic cells control the activity of origins of replication using multiple mechanisms, including multiple origins of replication and cell cycle checkpoints.Eukaryotic cells use multiple replication origins and checkpoints to prevent reactivation and ensure controlled DNA replication.
Step-by-step explanation:
Eukaryotic cells control the activity of origins of replication using multiple mechanisms to ensure that not a single origin is activated more than once during a cell cycle. One such mechanism is the presence of multiple origins of replication throughout the eukaryotic chromosomes. This allows for the initiation of DNA replication at different sites simultaneously, preventing the same origin from being activated more than once. Additionally, there are internal control mechanisms known as cell cycle checkpoints that monitor the progression of the cell cycle and halt it if conditions are not favorable for DNA replication. These checkpoints occur at the end of G1, the G2/M transition, and during metaphase.
Eukaryotic cells employ intricate mechanisms to tightly regulate the activation of origins of replication, ensuring their precise and controlled use during the cell cycle. The presence of multiple origins dispersed across chromosomes facilitates the simultaneous initiation of DNA replication at various sites, preventing the reactivation of a single origin. Complementing this spatial regulation, internal control mechanisms, known as cell cycle checkpoints, rigorously monitor cell cycle progression. These checkpoints, strategically positioned at the conclusion of G1, the G2/M transition, and metaphase, act as surveillance points, halting the cell cycle if conditions are unfavorable for DNA replication, thereby safeguarding genomic integrity.