PATHOLOGY

Detailed explanation-1: -The G 1start subscript, 1, end subscript checkpoint is the main decision point for a cell – that is, the primary point at which it must choose whether or not to divide. Once the cell passes the G 1start subscript, 1, end subscript checkpoint and enters S phase, it becomes irreversibly committed to division.

Detailed explanation-2: -Cell cycle has different stages called G1, S, G2, and M. G1 is the stage where the cell is preparing to divide. To do this, it then moves into the S phase where the cell copies all the DNA. So, S stands for DNA synthesis.

Detailed explanation-3: -G1 checkpoint – size and nutrient verification This checkpoint, also called the restriction checkpoint, takes place between the G1 and the S phase. The cell verifies that it is large enough to divide, that its DNA is intact, and if there is enough access to nutrients and stimulating growth factors.

Detailed explanation-4: -The point at G1 at which commitment occurs and the cell no longer requires growth factors to complete the cell cycle has been termed the restriction (R) point. The R point has been temporally mapped at 2–3 hours prior to the onset of DNA synthesis.

Detailed explanation-5: -At the G1/S transition, the G1 checkpoint occurs. At the G1 checkpoint, it’s determined whether the cell is large enough to divide, has enough nourishment for cell division, and is free of DNA damage.