Question

Which of the following statements is false? checkpoints of cell-cycle control system ensure that?

a. the environment is favorable for the cell to initiate dna replication.
b. the cell is 'big enough' to survive division all dna is replicated before m-phase begins.
c. m-phase is completed before cytokinesis begins.

Answer 1

The false statement among the options given is c, indicating that cytokinesis begins after the M-phase has completed, which is not the correct sequence of events in cell division. Cell cycle checkpoints, including the G1, S phase, and Mitosis checkpoints, ensure proper cell division and genetic integrity.

Step-by-step explanation:

The correct answer to this question is that statement c, "M-phase is completed before cytokinesis begins," is false. Checkpoints in the eukaryotic cell cycle are crucial internal control mechanisms that ensure the cell is ready to proceed to the next phase. There are three main cell cycle checkpoints:

• The G1 checkpoint ensures that the cell is large enough to divide and that the environment is favorable. If conditions are not met, the cell enters a resting phase or delays the transition to the S phase.
• The S phase checkpoint ensures that DNA has been replicated accurately before proceeding to mitosis.
• The Mitosis checkpoint (also known as the metaphase checkpoint) ensures that all chromosomes are properly aligned and attached to the spindle apparatus before anaphase can occur.

Each of these checkpoints helps prevent the propagation of damaged or incomplete cells, reducing the likelihood of developing mutations that can lead to conditions like cancer.