Abstract
The cell cycle is a process where cells are divided into two daughter cells. It is divided into two main phases: interphase and the mitotic (M) phase. During interphase, the cell grows, and duplicates its DNA. This phase includes the G1 phase, S phase (where DNA replication occurs), and G2 phase, where the cell prepares for division. The mitotic phase involves mitosis (prophase, metaphase, anaphase, and telophase) and cytokinesis, which physically divides the cell.
There are Several checkpoints, regulated by proteins like ATR, ATM, and p53, to ensure that the cell cycle proceeds without errors. If any issues are detected, the cycle pauses to fix them. This control helps prevent mutations. The process repeats as long as conditions allow the cell to grow.
In the cell cycle we have series of events that takes place in a cell where the cell divides into two daughter cell.
Cyclic events
Cell cycle
In the interphase- we have the G1 phase followed by S phase and then we have G2 phase then we jump to mitosis(M-phase) which is followed by cytokinesis then the cycle continues.
G1 Phase
In the G1 phase there is cellular content duplication except the chromosome like we get the mRNA synthetic that’s the transcription and we get the protein synthesis that’s the translation
When everything is good the cell processes into S-phase.
S-phase
At the S-phase that’s the synthesis phase that means here we get the synthesis of a DNA molecule which means DNA is duplicate here or we can say DNA replication takes place.
G2 phase
Then when the cell prossied into G2 phase the cell again rapidly grows and prepares itself for the mitosis and also there are quality control checks.
Prophase
Where chromatin condensed into chromosomes and nucleus disappears.
Metaphase
Whare chromosome line up along the imaginary metaphase plate.
Anaphase
Where chromosomes break at centromere and then the sister chromatin moves towards the opposite ends of the cell.
Telophase
Where the nuclear membrane reforms nucleus reappears and chromosomes unwind into chromatin.
Checkpoints
First check occur in G1 phase:
These checks are regulated by ATR, ATM, P53 and MDM2 protein. It checks for the DNA errors and breaks.
Intra S checkpoints:
Which is done by the same protein ATR, ATM, for DNA errors and breaks but in yeast it’s mediated by RPA protein and also by DDC protein, MEC protein and many other proteins.
G2 checkpoints:
Which is mediated by the same protein like ATM and ATR protein to check for the DNA errors, and finally we have the fourth checkpoints which is the SAC that spindle assembly checkpoints.
Mitotic checkpoints:
Complex which includes the BUBR1, BUR3, MAD2 and CDC20 protein. When all the checks are good and nothing is found to be complicated and compromised in the cellular content and there are no errors then only the cells process into the next phase.
