Question

Which of the following is false?

A. DNA synthesis begins at origins of replication
B. the loading of the origin recognition complexes (ORCs) is triggered by S-Cdk

Answer 1

The false statement is that the loading of the origin recognition complexes (ORCs) is triggered by S-Cdk, because ORC loading occurs in the G1 phase, not the S phase, and while S-Cdk activates ORCs for replication initiation, it is not responsible for their loading.

Step-by-step explanation:

The student has asked which of the following statements is false:

1. DNA synthesis begins at origins of replication.
2. The loading of the origin recognition complexes (ORCs) is triggered by S-Cdk.

The correct answer is statement B: The loading of the origin recognition complexes (ORCs) is triggered by S-Cdk. This statement is false because ORC loading occurs much earlier in the cell cycle; the ORCs are actually loaded during the G1 phase of the cell cycle, ahead of the S phase where DNA synthesis occurs. The activation of ORCs, leading to the initiation of DNA replication, is controlled by the action of S-Cdk, but the loading itself is not triggered by S-Cdk.