Final answer:
The correct option is 1. The cell cycle's M checkpoint ensures all chromosomes are correctly attached to the mitotic spindle before proceeding to anaphase. A mono-oriented chromosome would typically arrest the cycle, but manually correcting its orientation can fool the checkpoint, leading the cell to proceed to anaphase.
Step-by-step explanation:
The question pertains to the regulation of mitotic spindle attachments during mitosis, specifically the situation in which a mono-oriented chromosome could impact the progression of the cell cycle. At the M checkpoint, which occurs near the end of metaphase, the checkpoint ensures that each sister chromatid pair is correctly attached to spindle fibers from opposite poles. This is critical because the separation of sister chromatids during anaphase is irreversible. If a chromosome is mono-oriented, the M checkpoint would prevent the cell from proceeding to anaphase to avoid incorrect chromosome segregation.
If a glass micro needle were used to manually pull the mono-oriented chromosome towards the opposite pole, effectively mimicking correct bi-orientation, the checkpoint mechanisms might be satisfied, allowing the cell to proceed to anaphase. Therefore, the correct answer to the question is: 1) The cell proceeds to anaphase.