It is the process by which a parent cell divides into two or more daughter cells. Cell division usually occurs as part of a larger cell cycle. It is an essential biological process in many organisms. It is the means used by multicellular organisms in order to grow, repair, and reproduce.  Types of Cell division: Mitosis Meiosis Mitosis: Mitosis is a division of the nucleus to produce two new daughter cells containing chromosomes identical to the parent cell. Phases of Mitosis: Mitosis is a continuous process and divided into different phases based on the appearance and behavior of the chromosomes. Prophase Prometaphase Metaphase Anaphase Telophase Cytokinesis  1.Prophase: Early prophase: During prophase chromatin (the complex of DNA and proteins contained in the nucleus), condense and become visible in a light microscope Nucleolus disappears & Paired centrioles move to opposite ends of the cell. The replicated chromosomes have an X shape and are called sister chromatids. The sister chromatids are joined at a point called the centromere. Late prophase: Nuclear membrane disappears a structure called the mitotic spindle begins to form at opposite ends of the cell (responsible for separating the sister chromatids into two cells) 2. Prometaphase: Prometaphase is the second stage of mitosis. In prometaphase, Chromosomes continue to condense Kinetochores appear at the centromeres Mitotic spindle attach to kinetochores Centrosomes move toward opposite poles 3. Metaphase: Metaphase is the third step in mitosis. Mitotic spindle is fully developed Sister chromatids line up at the spindle equator At the end of metaphase, the centromeres start to divide 4.Anaphase: Anaphase begin with the separation of the centromeres Sister chromatids together break down Sister chromatids (now called chromosomes) are pulled toward opposite poles The sister chromatids are drawn to opposite poles of the cell by contraction of spindle fibers 5.Telophase: Telophase begin when the two sets of daughter chromosomes have reached the two poles of the cell. The spindle fibers breaks down, The nuclear membrane forms around each set of daughter chromosomes and the nucleoli reappear The chromosomes uncoil and become less visible under the light microscope 6. Cytokinesis: Cytokinesis is the sixth and final step of mitosis & A cleavage furrow separates the daughter cells Cytokinesis is the process of cytoplasmic division to form two daughter cells. Cytokinesis takes place when the Cytoplasm divides and two cells with identical genetic material are formed Daughter Cells Meiosis: Meiosis Takes place in the Gametes of an organism People have a Chromosome count of 46 When an egg joins a sperm the count must stay at 46 to remain human So, the egg can only have 23 chromosomes, and the sperm can only have 23 chromosomes But, the integrity of the organism must be maintained. During Meiosis diploid cells are reduced to haploid cells Diploid (2n) to Haploid (n): During Meiosis gamete (sex

1. Cell division
By,
M. Thiru murugan

2. • It is the process by which a parent cell divides into two or more
daughter cells. Cell division usually occurs as part of a larger cell
cycle.
• It is an essential biological process in many organisms. It is the
means used by multicellular organisms in order to grow, repair, and
reproduce.
• Types of Cell division:
• Mitosis
• Meiosis
• Mitosis: Mitosis is a division of the nucleus to produce two new
daughter cells containing chromosomes identical to the parent cell.
Cell division

3. •Phases of Mitosis:
•Mitosis is a continuous process and divided into different
phases based on the appearance and behavior of the
chromosomes.
1. Prophase
2. Prometaphase
3. Metaphase
4.Anaphase
5. Telophase
6.Cytokinesis

4. 1.Prophase:
• Early prophase:
• During prophase chromatin (the complex of DNA and proteins
contained in the nucleus), condense and become visible in a light
microscope
• Nucleolus disappears & Paired centrioles move to opposite ends of the cell.
• The replicated chromosomes have an X shape and are called sister
chromatids. The sister chromatids are joined at a point called the
centromere.
• Late prophase:
• Nuclear membrane disappears
• a structure called the mitotic spindle begins to form at opposite ends of
the cell (responsible for separating the sister chromatids into two cells)

5. 1.Prophase:

6. 2. Prometaphase: Prometaphase is the second stage of mitosis. In
prometaphase,
• Chromosomes continue to condense
• Kinetochores appear at the centromeres
• Mitotic spindle attach to kinetochores
• Centrosomes move toward opposite poles

7. 3. Metaphase:
• Metaphase is the third step in mitosis.
• Mitotic spindle is fully developed
• Sister chromatids line up at the spindle equator
• At the end of metaphase, the centromeres start to divide

8. 4.Anaphase:
• Anaphase begin with the separation of the centromeres
• Sister chromatids together break down
• Sister chromatids (now called chromosomes) are pulled toward opposite
poles
• The sister chromatids are drawn to opposite poles of the cell by contraction
of spindle fibers

9. 5.Telophase:
• Telophase begin when the two sets of daughter chromosomes have reached
the two poles of the cell.
• The spindle fibers breaks down,
• The nuclear membrane forms around each set of daughter chromosomes
and the nucleoli reappear
• The chromosomes uncoil and become less visible under the light
microscope

10. 6. Cytokinesis:
• Cytokinesis is the sixth and final step of mitosis & A cleavage furrow
separates the daughter cells
• Cytokinesis is the process of cytoplasmic division to form two daughter
cells.
• Cytokinesis takes place when the Cytoplasm divides and two cells with
identical genetic material are formed Daughter Cells

11. Mitosis

12. • Meiosis:
• Meiosis Takes place in the Gametes of an organism
• People have a Chromosome count of 46
• When an egg joins a sperm the count must stay at 46 to remain human
• So, the egg can only have 23 chromosomes, and the sperm can only
have 23 chromosomes
• But, the integrity of the organism must be maintained.
• During Meiosis diploid cells are reduced to haploid cells
• Diploid (2n) to Haploid (n):
• During Meiosis gamete (sex) cells undergo a double division,
maintaining the DNA, but reducing the chromosomal count to 23

13. • At the end of Meiosis the individual Gamete cell has divided
from one cell to four.
• Males produce 4 viable sperm.
• Females produce 1 viable egg and 3 non functioning polar
bodies.
• Meiosis is Two cell divisions (called meiosis I and meiosis
II) with only one duplication of chromosomes.
• Gametogenesis is the process of division of diploid cells to
produce new haploid cells. (Production of gametes)
• Meiosis in males is called spermatogenesis and produces
sperm.
• Meiosis in females is called Oogenesis and produces ova.

14. (46)
(46)
(23) (23)
(23) (23) (23) (23)
Diploid (2n)
Haploid (n)
• Spermatogenesis:
• 4 sperm cells are
produced from each
primary Spermatocyte.

15. • Oogenesis: Females produce 1 viable
egg and 3 non functioning polar
bodies. The polar bodies die… only
one ovum (egg) is produced from
each primary oocyte.

16. Meiosis
Original Gamete
Metaphase Anaphase Telophase Cytokinesis
2 Daughter Cells Metaphase 2 Anaphase 2 Telophase 2
Cytokinesis - 4
Gametes
Original Gamete Metaphase - 1 Anaphase - 1 Telophase - 1 Cytokinesis