Final answer:
The metaphase/anaphase transition is a crucial step in mitosis regulated by the M checkpoint, ensuring that sister chromatids are correctly attached to spindle fibers before separating and moving to opposite poles, guaranteeing that daughter cells have identical genetic material.
Step-by-step explanation:
The metaphase/anaphase transition is a critical phase in the cell cycle where cells progress from metaphase to anaphase during mitosis. This transition is carefully regulated by the M checkpoint, which assesses if all sister chromatids are properly attached to spindle microtubules. During metaphase, all chromosomes are aligned at the metaphase plate with sister chromatids joined together by cohesin proteins. Once all kinetochores are correctly attached to spindle fibers from opposite poles, the cell is allowed to proceed to anaphase.
In anaphase, cohesin proteins are cleaved, resulting in the separation of sister chromatids, which are then pulled towards opposite poles of the cell by shortening of the spindle microtubules. This transition ensures that each new daughter cell will receive an identical set of chromosomes, maintaining genetic continuity.
The sequence of mitosis stages is often memorized as prophase, metaphase, anaphase, and cytokinesis, which illustrates the orderly progression of cell division. It is essential to note that the metaphase/anaphase transition is irreversible, signifying the commitment of a cell to divide once the checkpoint's conditions are satisfied. Any problems in this transition can lead to improper chromosome segregation, potentially causing genetic disorders or diseases such as cancer.