What is the likely result if APC fails to ubiquitinate the M cyclin?

What is the likely result if APC fails to ubiquitinate the M cyclin?

• A. Cytokinesis will occur too soon
• B. Cytokinesis will be delayed
• C. The cell will die prematurely
• D. The M cyclin will be degraded correctly

Answer: (B)

The correct answer indicates that if APC (Anaphase Promoting Complex) fails to ubiquitinate M cyclin, cytokinesis will be delayed. APC is crucial for marking proteins for degradation, particularly during the transition from metaphase to anaphase in cell division. M cyclin is essential for driving the cell cycle into mitosis. When M cyclin is not ubiquitinated, it remains in the cell longer than it should. This prolonged presence of M cyclin keeps the cell in a state conducive to mitosis, which could lead to a delay in the normal exit from mitosis and subsequent cytokinesis. The inability to degrade M cyclin would result in the cell being unable to properly transition to the next stage of the cell cycle, specifically cytokinesis. Consequently, the ongoing cell division process is disrupted, leading to a delay in cytokinesis. Other potential outcomes like premature cell death or correct degradation of the M cyclin are not consistent with the consequences seen when ubiquitination does not occur. Rather, the failure of ubiquitination directly points to an inability to properly regulate the cell cycle's progression.

The correct answer indicates that if APC (Anaphase Promoting Complex) fails to ubiquitinate M cyclin, cytokinesis will be delayed. APC is crucial for marking proteins for degradation, particularly during the transition from metaphase to anaphase in cell division.

M cyclin is essential for driving the cell cycle into mitosis. When M cyclin is not ubiquitinated, it remains in the cell longer than it should. This prolonged presence of M cyclin keeps the cell in a state conducive to mitosis, which could lead to a delay in the normal exit from mitosis and subsequent cytokinesis. The inability to degrade M cyclin would result in the cell being unable to properly transition to the next stage of the cell cycle, specifically cytokinesis. Consequently, the ongoing cell division process is disrupted, leading to a delay in cytokinesis.

Other potential outcomes like premature cell death or correct degradation of the M cyclin are not consistent with the consequences seen when ubiquitination does not occur. Rather, the failure of ubiquitination directly points to an inability to properly regulate the cell cycle's progression.