Question

The precise replication of DNA is accomplished by the separation of the initiation of replication into two distinct steps. In the first step the origins are licensed or approved for replication. This step takes place early in the cell cycle when a(n) _____________________ attaches to an origin. In the second step the replication machinery initiates the replication at each licensed origin. The key is that the replication machinery functions only at licensed origins. As the replication forks move away from the origin, the __________________ is removed leaving the origin in an unlicensed state where replication cannot be initiated again until the ________ is renewed. To ensure that replication takes place only once per cell cycle the ____________________ is active only after the cell has completed mitosis and before the next replication is initiated.

Answer 1

The initiation of DNA replication involves two steps: licensing origins and replication initiation. Initiator proteins attach to origins in the first step, and replication machinery initiates replication at licensed origins in the second step. The process ensures replication occurs only once per cell cycle.

Step-by-step explanation:

The initiation of DNA replication involves two distinct steps. In the first step, an initiator protein attaches to the origin, which is a specific nucleotide sequence in the DNA. This step takes place early in the cell cycle. In the second step, the replication machinery initiates replication at each licensed origin. As the replication forks move away from the origin, the initiator protein is removed, leaving the origin unlicensed. Replication cannot be initiated again until the initiator protein is renewed.

To ensure replication takes place only once per cell cycle, the initiation process is active only after the cell has completed mitosis and before the next replication is initiated.