What happens in a cell cycle?

Every organism, from plants to humans to bacteria, has its life cycle. The life cycle is a development series with steps through which an individual goes from the time of birth to the time of death. 

Something similar happens in a cell cycle; it is a series of development and growth steps that a microcell goes through from birth to reproduction. The birth of a cell is the division of it from the mother cell, whereas its reproduction means the division of daughter cells. 

What Are the Stages of the Cell Cycle?

The cell cycle is not linear and is a never-ending loop where the two divided daughter cells from mother cells start and end in the same process. There are various important tasks that a cell has to complete, from growing to copying DNA material and to splitting into daughter cells. 

In the case of the eukaryotic cell or any other cell which has a nucleus, the cell cycle is divided into two stages, i.e., Interphase and Mitotic Phase. In the interphase, a cell grows completely and then copies genetic material called DNA. In the mitotic phase, the cell with DNA separates into two parts, dividing its cytoplasm and forming two new daughter cells. 

What Happens in the Interphase Cell Cycle?

This phase deals with the division of a cell from its mother cell, its growth, and then a copy of genetic materials called DNA. The term “inter,” which is the prefix in interphase, means “in-between.” Here, interphase is the phase between two mitosis phases of mother and daughter cells. There are three steps involved in this interphase known as the G1 Phase, S Phase, and G2 Phase.

1.G1 Phase

​This phase is also known as the 1st Gap Phase. Here, the daughter cell physically grows, copies the organelles, and also builds molecular blocks in the end. 

2.S Phase

In this phase, the cell copies the genetic material known as DNA in the nucleus. Here, in this phase, the cell also makes a copy of the microtubule organising structure, which is known as the centrosome. This centrosome helps separate the DNA in the mitotic phase of the cell. 

3.G2 Phase

This is also known as the 2nd Gap Phase. Here, the cell grows more in size and makes organelles and proteins. Also, in this stage, the cell starts preparing and reorganising its material for the mitosis process. As soon as the 2nd Gap phase ends, the Mitosis phase begins in the cell cycle. 

What Happens in the Mitosis Phase Cell Cycle?

In this phase, the cell divides its cytoplasm and copies genetic material DNA in two new daughter cells. This stage involves two different processes related to division: Cytokinesis and Mitosis. 

1.Mitosis

In this stage, the DNA, i.e., the nuclear, condenses in multiple visible chromosomes. Then these materials are pulled apart with the help of a specialised material which is made of microtubules and the mitotic spindle. The mitosis phase happens in four stages:

• Prophase (Also divided as early prophase and pro-metaphase)
• Metaphase
• Anaphase
• Telophase

2.Cytokinesis

In this phase, the cell splits into two new daughter cells. This stage begins when mitosis ends, which has some level of overlapping. Also, cytokinesis is different in both plants and animals.

• Animal Cell:

Here, the division of the cell happens with the cytoskeletal fibres band, which is known as the contractile ring. The contraction of this ring inwards pinches the cell into two new cells, and this whole process is known as contractile cytokinesis. Also, the indention which is produced in the process of inward contraction of the ring is known as cleavage furrow. It is easy to pinch in the case of an animal cell because it is relatively more squishy and soft. 

• Plant Cell:

In comparison to animal cells, these cells are stiffer, and they are also surrounded by a rigid wall called the cell wall. Also, they have high internal pressure because the division method here is different from animal cells. These plant cells divide into two daughter cells by building a new structure in the middle of the plant cell. This structure is called a cell plate and is made of the same components of the cell wall and plasma membrane.  

What Happens After Daughter Cells Are Produced –  The G0 Phase of the Cell Cycle?

This depends on the cell type; if it divides rapidly, another phase of cell division will start, i.e., interphase. Example: early embryo cell division and cell division in the tumour. 

​The other type of cell divides slowly or doesn’t divide at all. Here, the cell, after exiting the First G phase, directly enters the resting phase of G0. These cells don’t actively participate in division and do special jobs. Example: stores carbohydrates (Liver cells) conducts signals (Neurons). 

What Happens in the Cell Cycle: Duration of One Complete Cell Cycle

The length of time for a complete cell cycle is different for different cells. Example: A human cell can also take 24 hours to the division, or fast cycling cells like the one in the intestine can complete their cycle in 9 to 10 hours. 

Also, different cells take a different amount of time in different phases of the cell cycle. Example: A frog embryo spends more time in the first and second G phase and less in S and Mitotic phases. This results in the division of zygotes in many small cells. 

Conclusion

The cell cycle is not linear and is a never-ending loop where the two divided daughter cells from the mother cells start and end in the same process. There are various important tasks that a cell has to complete, from growing to copying DNA material to splitting into daughter cells. Through the above-mentioned information, we have come to know what happens in a cell cycle and the stages involved in the cell cycle.