Biology notes [CELL DIVISION & CELL CYCLE]

Cell Division & Cell Cycle

Cell Division

### Definition:  It is the process of formation of identical cells that may resemble the parents and contribute in the maintanence of the species of the organism.

### Types of Cell Division: 

              1.Mitosis      It is the process of the division of the cell to form two daughter cells ,the ploidy of which is the same as the diploid number of the parent cell.

                            example :    2n divides into 2n and 2n ,

                                  further   2n divides into 2n and 2n 

                                 similarly  2n divides into 2n and 2n ( i mean , that in each cell division by mitosis , the ploidy remains the same )

               

               2.Meiosis   It is the process of the division of the cell in which four daughter cells are formed , the ploidy of which is half of the diploid number of the parent cell.

                           eg :   2n divides into n , n, n, n .

 ### Difference  between Mitosis and Mieosis : 

                    Mitosis                                                       Meiosis

              1.Two daughter cells are formed                 1.Four daughter cells are formed.

              2.Daughter cells have Ploidy(Diploid)          2.Daughter cells have Ploidy(Haploid)

                   same as the parent cell(2n)                         half of the parent cell(n).

              3.It occurs in Somatic Cells.                        3.It occurs in Reproductive Cells.

                 

Cell Cycle

### The cell , which is supposed to take part in cell division , always undergoes a cycle described as the Cell Cycle.

       Cell Cycle consists of four phases/steps-

                       1. G1 phase

                        2. S phase

                       3. G2 phase

                        4.M phase

 ### Some terms related to Cell division.

                    Karyokinesis :- It is the term used to describe the division of the nucleus of the cell to form daughter nuclei.

                   Cytokinesis :-It is the term used to describe the division of the Cytoplasm of the cell to form Daughter cells.

### Phases of Mitosis          

         1. Prophase

         2.Metaphase

         3.Anaphase

         4.Telophase

###Phases of Meiosis

         1.First Meiotic Division.

         2.Second Meiotic Division.

### Significance of Mitotic Division : * Helps organisms to reproduce asexually.
                                                               * Helps organisms to regenerate worn out cells.

### Significance of Meiotic Division : *Helps organisms reproduce sexually.

###Difference between Mitotic and Meiotic Division
                       Mitotic Division                                               Meiotic Division

              1.Two daughter cells are formed                 1.Four daughter cells are formed.

              2.Daughter cells have Ploidy(Diploid)          2.Daughter cells have Ploidy(Haploid)

                   same as the parent cell(2n)                         half of the parent cell(n).

              3.It occurs in Somatic Cells.                        3.It occurs in Reproductive Cells.
              4.Occurs in mainly 4-phases.                       4.Occurs in mainly 2-phases
                  namely, Prophase-Metaphase-                      namely,First Meiotic Division and
                            Anaphase-Telophase.                             Second meiotic Division.

 

                                                       

                  

      (Mobile users, please view using web version)