Step 1

Cell division is the method through which a parent cell divides into 2 or more daughter cells. The cell is the basic unit of life and it is the basis of the survival of organisms. All living organisms are made up of cells. If the cell does not divide then no new organism will originate. The existing cell will die after some time. New cells arise when there is a process named cell division occurs but when cell division does not occur then no new cells will be produced as there is no cell division. The cell division process by which cells multiply involves both cytoplasmic and nuclear division.

Step 2

Cell cycle regulation is important without cues to grow or to stop growing. Cells would either multiply non-stop forming masses or they would never multiply. There are three major checkpoints in the cell cycle at the end of G1, end of G2 and during metaphase progression through checkpoints is mediated by cyclins, CDKs, and tumor suppressors.

The following four phases are the main stages of the cell cycle:

G1 (first gap phase) - It is the interval between cell division and deoxyribonucleic acid replication. Cell synthesizes proteins, grows, carries out bodily tasks, and prepares for replication; takes 8 to 10 hours.
S (synthesis phase) - In this phase, the cell makes a copy of centrioles and DNA. Thus the duplication of the genetic material (about 99.7%) occurs in this phase. This is the phase that follows the G1 phase and lasts for about 6 to 8 hours.
G2 (second gap phase) - this phase is the next phase to the synthetic phase. It is the interval between DNA replication and cell division. Cell finishes replication and synthesizes enzymes for cell division; lasts 4 to 6 hours.

4 M (mitotic phase) - The nuclear and cell division are the prominent activities in this phase. Therefore, ultimately result in the formation of the two daughter cells. This phase lasts for about 1 to 2 hours.

Step 3

Cell cycle regulation is the process that controls the sequence of events through which a cell goes through the cell cycle. Each step of the cell cycle is monitored by internal controls known as checkpoints.

Specific points in the cell, called checkpoints enable the cell cycle to proceed or stop from continuing cell division, which is dependent on the genes controlled. The mitosis cell cycle consists of three checkpoints. They are:

G1 or Gap phase-1 checkpoint: During the G1 phase of the cell cycle, all the cell organelles increase in number and accumulate for DNA synthesis. If DNA is damaged in this stage, the cell cannot proceed to the next stage and leads to apoptosis that terminates the cell cycle. Thus cell cycle needs a gap phase-1 checkpoint to check all the components of the cell to enter into the next phase.
G2 or Gap phase-2 checkpoint: During the G2 phase of the cell cycle. DNA and proteins are synthesized for cell division. So the checkpoint verifies whether the DNA has replicated or not and proceeds to a new stage i.e. mitosis. If there is any DNA damage, apoptosis takes place to retrieve the cell cycle.
M or Mitosis checkpoint: It is the spindle assembly checkpoint. This checkpoint verifies the proper alignment of the chromosomes during cell division. If chromosomes are not aligned properly, mitosis cannot proceed and leads to apoptosis that terminates cell division.

Make a creative short story about the phases of cell cycle and its checkpoints. Highlight each function of the checkpoints and the charactericstics of the cell during the different stages of the cycle.

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