What is Cell division and its types?

Cell Division- Cell division is a process in which the single cell divide or multiply into two or more identical cells. It play important role in growth, reproduction and repair.

There are three types of cell division- 

1) Amitosis

2) Mitosis

3) Meiosis

1) Amitosis- is the process in which the cell is directly divide into two daughter cell without any formation of spindle and appearance of chromosomes. The nucleus present inside the cell elongates and develops a constriction round its middle. This constriction gradually deepens and finally cuts the nucleus into two daughter cells. Example- Paramecium divide by amitosis.  

2) Mitosis- is the process in which two identical daughter cell produced by a single parent cell by karyo-kinesis, cytokinesis and cell separation. The daughter cells carry same amount of DNA, same amount and kind of Chromosomes and same hereditary instruction from parent cell so that this division also known as equational division. It occur in all kind of eukaryotic cells.

Types of Mitosis- There are four types of mitosis.

 

i) Intranuclear and Extranuclear Mitosis

ii) An-astral and Am-phi-astral Mitosis

iii) Endomitosis

iv) Free Nuclear Division

i) Intranuclear and Extranuclear Mitosis-

Intranuclear Mitosis- is the process in which the division occur inside the nucleus along with nuclear envelope. Nucleus is divide by furrowing process along with cytoplasm. It occur in unicellular organisms like yeast and amoeba. This process is also known as pre-mitosis.

Extranuclear Mitosis- It is the process the nuclear envelope breakdown and division occur in cytoplasm. It occur in Multicellular organisms. This process is also known as Eu-mitosis.

ii) An-astral and Am-phi-astral Mitosis-

An-astral means no asters. In some cells there are no centrioles and no asters are formed during cell division known as An-astral Mitosis. Plant cells divide by an-astral mitosis.

 Am-phi-astral Mitosis- The cells divided by forming asters, the process known as Am-phi-astral Mitosis. Animal cells divide by Am-phi-astral mitosis. 

iii) Endomitosis- is the process in which number of chromosomes set, increase in the cell. During the division the chromosomes and DNA replicate but nuclei did not divide, it rise number of chromosomes in the cell. This process is also called endoduplication. It occur in Cells of mammalian liver. 

iv) Free Nuclear Division-means continuous nuclear multiplication. In some cases the nucleus divide repeatedly without cytoplasm division. It produce multi-nucleated cells. Fungi and endosperm cells of some seed plants are the example of free nuclear division. 

3) Meiosis- is the process in which one parent cell divide into four daughter cells. It consist two division meiosis-I and meiosis-II but the chromosomes are only replicate once. Meiosis also known as reduction division because the four daughter cell contain half number of chromosomes and half number of DNA amount from parent cell. It occur in special cells and at specific times.  

Types of Meiosis-  There are three types of meiosis-

i) Gametic or Terminal Meiosis-  The Meiosis take place before the fertilization during the formation of gamete known as Gametic or terminal meiosis. It occur in many protozoans, animals and some lower plants.

ii) Zygotic and Initial Meiosis-  in this, the fertilization is immediately followed by meiosis in the zygote and produce adult organisms are haploid. This type of meiosis is known as Zygotic or initial meiosis. It occur in some fungi, and some algae. 

iii) Sporo-genetic or Intermediate meiosis- in this type of meiosis, in some plants, gametes are formed by mitosis and meiosis occur at the time of spore formation. Spore are formed from the zygote in primitive form and from the spore mother cells in other. Meiosis in zygote in the former case and Sporo-genetic in the latter case. 

For Basic Knowledge about Mitosis and Cell go through these links :-

 

https://easylearningwithned.blogspot.com/2022/12/what-is-mitosis.html

https://easylearningwithned.blogspot.com/2022/11/what-is-cell-discovery-types-structure.html

Reference book- Pradeep's Biology Text Book .