Once the _______ checkpoint is passed in the cell cycles, the cell is committed to division
Once the restriction point checkpoint is passed in the cell cycle, the cell is committed to division.
To understand how this checkpoint works, let's first explore the cell cycle. The cell cycle is a series of events that a cell goes through to divide and produce new cells. It consists of four main phases: G1 (Gap 1), S (Synthesis), G2 (Gap 2), and M (Mitosis).
During the G1 phase, the cell grows in size and performs various functions necessary for survival. At the end of the G1 phase, the cell reaches a critical decision point called the restriction point checkpoint or the "R" point.
The restriction point checkpoint is an important regulatory checkpoint in the cell cycle. It determines whether the cell will continue towards division or enter a non-dividing state called the G0 phase, where it can remain indefinitely. This decision is based on various factors such as the size of the cell, nutrient availability, growth factors, DNA damage, and overall cell health.
Passage through the restriction point checkpoint requires the proper activation of specific proteins called cyclin-dependent kinases (CDKs), which are responsible for controlling the progression of the cell cycle. These CDKs need to bind with specific proteins called cyclins to become active.
If the cell receives adequate signals at the restriction point checkpoint, the CDK-cyclin complexes are activated, promoting the cell to enter the S phase. In the S phase, DNA replication occurs, and the genetic material is duplicated.
Once the cell has successfully passed the S phase and entered the G2 phase, it undergoes another checkpoint called the G2/M checkpoint. At this checkpoint, the cell checks for DNA damage and ensures the replication process is completed accurately.
If the DNA is undamaged, and the replication is successful, the cell proceeds to the M phase, which includes mitosis and cytokinesis, eventually leading to the division of the cell into two daughter cells.
In summary, once the restriction point checkpoint in the G1 phase is passed, the cell is committed to division, and it will proceed through the S, G2, and M phases, ultimately resulting in cell division.