CELL CYCLE REGULATION
The Regulation of the Cell Cycle
The cell cycle is an essential event that occurs in every living body, and it must be properly regulated for
cells to function properly.
Understanding the Cell Cycle
The cell cycle can be separated into two primary stages: interphase and mitosis. Interphase is further
divided down into three stages: G1, S, and G2. During G1, the cell grows and prepares for DNA replication,
which occurs in the S phase. Following DNA replication, the cell enters the G2 phase, which is when it
prepares to divide. Mitosis has four stages: prophase, metaphase, anaphase, and telophase, followed by
cytokinesis.
Checkpoints in the Cell Cycle
The cell cycle includes three significant checkpoints: the G1/S, the G2/M, and the M checkpoint. These
checkpoints ensure the cell cycle occurs normally and that any defects are fixed before the cell divides.
G1/S Checkpoint
The G1/S checkpoint occurs as the G1 phase transitions into the S phase. The cell checks for DNA damage
or mutations at this checkpoint before entering the S phase and replicating its DNA.
G2/M Checkpoint
The G2/M milestone marks the shift from the G2 to the M phases. This checkpoint guarantees that the
cell's DNA is properly copied and that it is prepared to undergo mitosis.
M Checkpoint
Before the cell enters anaphase, the M checkpoint ensures that the chromosomes are correctly positioned
on the metaphase plate during mitosis.
Genes Involved in the Regulation of the Cell Cycle
There are two main types of genes involved in the regulation of the cell cycle: proto-oncogenes and tumor
suppressor genes.
Proto-Oncogenes
Genes known as proto-oncogenes promote cell division. They generate proteins that facilitate the cell
cycle's progression from one stage to the next. A few instances of proto-oncogenes are cyclin D, E, and A.
