The Power of Cell-Cycle Checkpoints: Ensuring Cell Health and Division Success
What are the major events associated with the three main cell-cycle checkpoints?
A) G1/S phase checkpoint: DNA replication; G2/M phase checkpoint: Mitotic spindle formation; M phase checkpoint: Sister chromatid separation.
B) G1/S phase checkpoint: Cell growth and preparation for DNA synthesis; G2/M phase checkpoint: DNA repair and final preparations for cell division; M phase checkpoint: Initiation of mitosis.
C) G1/S phase checkpoint: Mitosis initiation; G2/M phase checkpoint: Centriole duplication; M phase checkpoint: DNA replication and chromosome condensation.
D) G1/S phase checkpoint: Sister chromatid separation; G2/M phase checkpoint: DNA replication; M phase checkpoint: Initiation of cell cycle.
The Major Events Associated with Cell-Cycle Checkpoints
Final Answer: The major events associated with the three main cell-cycle checkpoints are assessing the cell size and DNA damage, checking for proper chromosome replication, and ensuring correct chromosome segregation during mitosis.
The cell cycle is a highly regulated process that ensures the proper growth, development, and division of cells. At key points in the cell cycle, known as cell-cycle checkpoints, specific events are closely monitored to maintain cell health and ensure successful cell division. Let's explore the major events associated with the three main cell-cycle checkpoints:
G1/S Phase Checkpoint:
The G1/S phase checkpoint occurs just before a cell enters the synthesis (S) phase of the cell cycle, where DNA replication takes place. At this checkpoint, the cell size is assessed to ensure it is large enough to divide. Simultaneously, the checkpoint also checks for any DNA damage that may have occurred during the cell's growth and preparation for division.
G2/M Phase Checkpoint:
Prior to entering the mitotic (M) phase of the cell cycle, the G2/M phase checkpoint evaluates whether all chromosomes have been accurately replicated and confirms that the replicated DNA is intact. Any abnormalities in DNA replication or damage are detected and addressed at this crucial checkpoint to prevent potential errors in cell division.
M Phase Checkpoint:
The M phase checkpoint occurs near the end of metaphase, the stage of cell division where chromosomes align in the center of the cell before segregation. At this point, the checkpoint ensures that all sister chromatids are correctly attached to spindle microtubules, ready for proper chromosome segregation during anaphase. This meticulous process safeguards the integrity of genetic material during cell division.
By meticulously monitoring these key events, cell-cycle checkpoints play a vital role in safeguarding the integrity of cellular DNA, promoting accurate chromosome replication and segregation, and ultimately ensuring the successful division of healthy cells.