Cell Division; Mitosis and Meiosis

1. Cell ReproductionBy: Mr. Nikko Lorenz Lawsin

2. Outline of the Discussion
Cell Reproduction and its importance
Difference of Mitosis and Meiosis
Cell cycle
Phases of Mitosis and Meiosis
Gametogenesis (Spermatogenesis and Oogenesis)

3. Cell Reproduction
Formation of
cells of the same
kind.
It has two cellular
processes known
as Mitosis and
Meiosis.
Cell
reproduction
Mitosis Meiosis

4. Importance of Cell Reproduction
Growth (increase in size)
Maintenance of the organism
 Repair and Replacement of
cells/tissues that were worn out
Perpetuation of Species

6. MitosisProduction of two daughter cells with the same
chromosomal number to parent cell
Sample exercise 1:
1. There are 2, 472 parent cells. Each cell has 7 chromosomes.
a. After mitosis, how many daughter cells will be produced?
b. After mitosis, how many chromosomes does a daughter cell
have?
2. There are 2, 472 daughter cells. Each cell has 12
chromosomes.
a. Before mitosis, how many parent cells were there?
b. Before mitosis, how many chromosomes does parent a cell
have?

7. Meiosis
Production four daughter cells with half chromosomal
number as compared to parent cell.
Sample exercise 2:
1. There are 2, 472 parent cells. Each has 10 chromosomes.
a. After meiosis, how many daughter cells will be produced?
b. After meiosis, how many chromosomes does a daughter cell
have?
2. There are 2, 472 daughter cells. Each has 12 chromosomes.
a. Before meiosis, how many parent cells were there?
b. Before meiosis, how many chromosomes does parent a cell
have?

8. Cell Cycle

9. Cell Cycle

10. Cell Cycle

11. Mitosis in Plants

12. Mitosis in Plants

13. Significant Changes
Phases of Mitosis
Prophase,
- Disappearance of nuclear
membrane and nucleolus.
- Chromosomes are now open for
attachment.

14. Significant Changes
Phases of Mitosis
Metaphase,
- Chromosomes are singly aligned
at the center (metaphase
plate/equatorial plate).
- Genes in the chromosomes are
aligned properly.

15. Significant Changes
Phases of Mitosis
Anaphase,
- Disjunction of the sister
chromatids upon the cut of
centromere that binds the
chromosome.
- Disappearance of spindle fibers
except asters

16. Significant Changes
Phases of Mitosis
Telophase,
- Reappearance of nuclear
membrane and nucleolus
- Division of nucleolus (karyokinesis)
- Division of the cytoplasm or entire
cell (cytokinesis)

17. Significant Change... Starts with YOU.
Phases of Mitosis

18. Significant Changes
NOTE:
Prophase, Metaphase, Anaphase and Telophase;
The cellular process is MITOSIS.
Prophase I, Metaphase I, Anaphase I and
Telophase I, and;
Prophase II, Metaphase II, Anaphase II and
Telophase II;
The cellular process IS MEIOSIS.

19. Significant Changes
Phases of Meiosis
Prophase I,
- In synapsis, homologous
chromosomes loosely pair up,
aligned gene by gene so it will be
equally distributed in the pair of
chromosomes
- Nuclear membrane tends to
disappear

20. Significant Changes
Phases of Meiosis
Metaphase I,
- Movement of the chromosomes
(double-aligned) to the
equatorial or metaphase plate.

21. Significant Changes
Phases of Meiosis
Anaphase I,
- pairs of homologous chromosomes
separate
- One chromosome moves toward
each pole, guided by the spindle
apparatus, but;
- Sister chromatids remain attached
at the centromere and move as
one unit toward the pole

22. Significant Changes
Phases of Meiosis
Telophase I,
- each half of the cell has a haploid
set of chromosomes; each
chromosome still consists of two
sister chromatids
- Cytokinesis usually occurs
simultaneously, forming two
haploid daughter cells

23. Significant Changes
NOTE:
The CHANGES in Meiosis II are also observable or
the same in MITOSIS

24. Significant Changes
Phases of Meiosis
Prophase II,
- Disappearance of nuclear
membrane and nucleolus.
- Chromosomes are still composed
of two chromatids.

25. Significant Changes
Phases of Meiosis
Metaphase II,
- Movement of the chromosomes (the
sister chromatids are arranged at the
metaphase plate.
- Because of crossing over in meiosis I,
the two sister chromatids of each
chromosome are no longer
genetically identical because of the
crossing over

26. Significant Changes
Phases of Meiosis
Anaphase II,
- the sister chromatids separate
moving toward opposite poles

27. Significant Changes
Phases of Meiosis
Telophase II,
- Nuclear membrane and
Cytokinesis separates the
cytoplasm
- At the end of meiosis, there are
four daughter cells (genetically
distinct from the others ), each
with a haploid set of
unreplicated chromosomes

28. Significant Changes
Review:
Identify the phases (Mitosis/Meiosis) where the
following changes can be observed.

29. Significant Changes
Review:
pairs of homologous chromosomes separate
Anaphase I

30. Significant Changes
Review:
- Chromosomes are singly aligned at the center
(metaphase plate/equatorial plate).
Metaphase

31. Significant Changes
Review:
each half of the cell has a haploid set of
chromosomes; each chromosome still consists of
two sister chromatids
Telophase I

32. Significant Changes
Review:
Disappearance of nuclear membrane and
nucleolus resulting the chromosomes are now
open for attachment.
Prophase

33. Significant Changes
Review:
the sister chromatids separate moving toward
opposite poles
Anaphase II

34. Significant Changes
Review:
- Production of four daughter cells (genetically
distinct from the others ), each with a haploid
set of unreplicated chromosomes
Telophase II

35. Significant Changes
Review:
pairs of homologous chromosomes separate
Anaphase

36. Significant Changes
Review:
Movement of the chromosomes (double-
aligned) to the equatorial or metaphase plate.
Metaphase I

38. Gametogenesis
Gametogenesis,
- “Gameto-” means gametes while “-genesis”
means formation
1. Spematogenesis – formation of sperm cells.
2. Oogenesis – formation of egg cells.

39. Spermatogenesis

40. Oogenesis