Cell Division

The process through which a parent cell is separated into two or more daughter cells is called cell division, and it generally occurs in the form of a bigger cycle of cells. In simpler words, cell division is when the cell divides itself to form new cells. For living organisms like plants, animals, bacteria, and humans, the division of a cell to restore used and worn-out cells is a unique trait. The process of cell division is very fundamental in the course of an organism’s life as it helps in growth, reproduction, and repair. It is also significant for the renewing of the cells that are damaged.

Vegetative division and reproductive cell 

There are two different types of division of cells in eukaryotes. One of the divisions is a vegetative division. A daughter cell is similar and identical to the parent cell. And the other type of division of cells is called a reproductive cell division, in which half lessens the chromosome number in the daughter cells to give haploid gametes. Another part of the cycle of cells is called mitosis; in this process, the replicated chromosome is divided into two brand new nuclei. 

Genetically identical cells rise in the cell division where the total chromosome number is under control. In simpler words, it is called mitosis or the division of the nucleus. The vegetative division of cells that happens in the bacteria and archaea or prokaryotes is called binary fission. In binary fission, the genetic content is bound into two equal daughter cells—the alternate form of binary fusion in prokaryotes of budding. However, the type of species organism, the division of cells, is followed by an individual round of replication of DNA. 

Cell division in reproduction 

Organisms like the amoeba, a single-cell organism, reproduce through cell division. An entire complete new amoeba is created with the division of its single cell. The primary and the most prominent role of cell division is to maintain the genome or the genetic information of the original cell. In the bigger picture, the meiotic division of the cell can create a part of an organism from a multicellular organism, such lizards can grow their tail, or plants can grow branches from the break-off. A frog can also grow its body parts by regenerating and multiplying the cells. 

Bacteria cell division

The division of cells in bacteria occurs through budding and binary fission. A protein component called divisome is present in the bacteria and is considered responsible for cell division. 

Eukaryotes cell division

The division of cells in eukaryotes is far more complex than the cell division in prokaryotes. The cell division of eukaryotes can be divided into mitosis and meiosis based on reducing the chromosome number. Amitosis is an early or ancient form of cell division. The amitotic or mitotic division of the cell is more diversified.

Mitosis

There are six stages of mitosis. 

1. Interphase

During interphase, a cell goes through the G1 phase, S phase, and G2 phase. 

• G1 phase: this is the phase before DNA synthesis 
• S phase: this is the phase of synthesis of DNA.
• G2 phase: this is the period between the end of the synthesis of DNA and the start of the prophase. 

2. Prophase

In this process, the formation of chromosomes starts. It is composed of 2 chromatids. This phase completes when the assembly of the spindle initiates. Components like proteinaceous and microtubules help in this process. The disintegration of the nucleus envelope starts. 

3. Prometaphase

In this phase, the disintegration of the nucleus is completed. Chromosomes in the cell are allowed to move through microtubules that are attached to kinetochores.

4. Metaphase

In this phase, chromosomes come in the middle of the cell. This state is known as the metaphase plate. Each cell gets its own genome. 

5. Anaphase

In this phase, sister chromatids are split up. They become daughter nuclei. The centromere of every chromosome is on the edge and their arms trail behind them. 

6. Telophase

In this phase, the formation of the nucleus envelope starts. The components of cells like ER complex, Golgi bodies, and nucleolus start to reappear as they disappear during prophase. 

Meiosis

The stages of meiosis 1 are given below. 

Meiosis 1 

In this stage, the homologous chromosome is separated and divided into two cells. 

1. Prophase 1: small parts of homologous chromosomes are exchanged so that one chromosome contains both maternal as well as paternal DNA. This process is also known as crossing over. 
2. Prometaphase 1: in this phase, the process of condensation of chromosomes continues. 
3. Metaphase 1: maternal as well as the paternal version of a chromosome come in the middle of the cell. This leads to the diversity of offspring. 
4. Anaphase 1: in this phase, the retraction of spindle fibres takes place. The DNA is divided equally into the cells that will form. 
5. Telophase 1 and cytokinesis 1- during telophase 1, spindle fibres start disappearing, and the envelope of the nucleus starts to form again. 

In cytokinesis 1, the division of cytoplasm and cell takes place. Each chromosome gets two chromatids.

Meiosis 2

1. Prophase 2 and prometaphase 2: These stages are the same as those in meiosis 1.
2. Metaphase 2: Chromosomes start to line up in the form of homologous pairs. 
3. Anaphase 2: Sister chromatids start to be pulled towards opposite poles of the cell in the equator. 
4. Telophase 2: This stage is the same as that of meiosis 1.
5. Cytokinesis 2: Two non-identical daughter cells (haploid) are formed. This process took place in meiosis 1, so there are a total of 4 non-identical daughter cells. They fully form gametes. 

Variants of cells

Cells can be divided into two main classifications –non-nucleated simple prokaryotic cells and nucleated complex eukaryotic cells. Because of the difference in the structure of the cells, the eukaryotic and prokaryotic division of cells happens differently. The eukaryotic stem cells that are transformed into gametes are called meiosis. Somatic cell division in the organism’s body is different from meiosis. Through the division of cells, multicellular organisms restore the used cells. 

Conclusion

To conclude the topic of cell division, we understand that cell division is an essential part of living organisms. The cell divides it and replicates a brand new cell. In the cell division, the parent cell is separated into two or more new daughter cells. For all living organisms like plants, animals, bacteria, and humans, the division of a cell to restore used and worn-out cells is a unique trait. There are two types of cell division: meiosis and mitosis. In mitosis, the cell duplicates its all components, including the chromosome, and then spills into two new daughter cells. In meiosis, the same number of chromosomes is maintained in every generation. The cell division of eukaryotes is more complex than the cell division of the prokaryotes. Through budding and binary fusion, the cell division of bacteria happens.