Which checkpoint checks if the chromosomes are properly aligned during cell division?

The checkpoint that verifies whether the chromosomes are properly aligned during cell division is the metaphase checkpoint. This checkpoint is a crucial part of the cell cycle, specifically during mitosis, when the cell ensures that all chromosomes are correctly positioned along the metaphase plate before proceeding to anaphase.

Proper alignment is essential because it allows for an equal distribution of chromosomes to the daughter cells. If the chromosomes are not aligned correctly, the cell can halt the process until the issue is resolved, preventing potential errors in chromosome segregation, which could lead to conditions such as aneuploidy.

The other checkpoints, such as the G1 and G2 checkpoints, focus on different aspects of the cell cycle. The G1 checkpoint assesses the cell's size, DNA integrity, and environmental conditions before committing to DNA synthesis, while the G2 checkpoint ensures that DNA has been completely and accurately replicated before moving into mitosis. The anaphase checkpoint, while also important, occurs after metaphase and is responsible for ensuring that the sister chromatids are ready to be pulled apart, not for checking their alignment.