What happens when a cell bypasses the G1 checkpoint?

• A. It continues to S phase without restriction
• B. It enters apoptosis
• C. It undergoes differentiation
• D. It stops functioning

Answer: (A)

When a cell bypasses the G1 checkpoint, it continues to the S phase of the cell cycle without the regulatory checks typically in place. The G1 checkpoint is crucial for assessing various factors, including cell size, DNA integrity, and the availability of nutrients. If a cell successfully passes this checkpoint, it implies that conditions are deemed favorable for division, allowing the cell to replicate its DNA and proceed to S phase.

This unchecked progression can lead to issues, such as uncontrolled cell division, which is a characteristic of cancerous cells. However, in this context, the primary consequence of bypassing the G1 checkpoint is the advancement into the S phase, where the cell actively prepares for mitosis.