Lesson 5 Cell Cycle (Mitosis and Meiosis)

General Biology 1 for STEM students

1. Cell Cycle: Mitosis and Meiosis
Prepared by:
MR. KEVIN FRANCIS E. MAGAOAY
Faculty, SHS Biology Department
C h a p t e r 5

2. Learning Objectives:
Characterize the phases that a normal cell
undergo
Demonstrate understanding in the process of
cell division
Illustrate the events of cell cycle
Compare and contrast each phase

3. Overview:
Definition of Cell Cycle
Why do cells need to undergo cell cycle process
Stages of Cell Cycle

4. What is Cell Cycle?
Can be thought as the life
cycle of the cell
It is an ordered series of
events involving cell growth
and development steps a
cell undergoes to make two
new daughter cells
It is a cycle rather than a
linear pathway

5. Why do cells have to undergo
Cell Cycle process?
For growth
For cell differentiation
For repair and healing of damaged tissues
For replication of genetic materials
For reproduction of species

6. Cell Division
Eukaryotic Prokaryotic
Mitosis
Meiosis
Binary Fission

7. Binary Fission Mitosis and Meiosis

8. Cell Cycle

9. Interphase
Non dividing phase
Longest stage of cell
cycle
The cell grows and copies
its chromosomes in
preparation for cell
division

Centrioles Chromatin
Nuclear
envelope
Plasma
membrane
Nucleolus

10. ??????
�Phase
First Gap Phase
Cell increases in volume
Cell preparing all the
chemicals necessary for
DNA synthesis
Duplication of organelles
Centrioles Chromatin
Nuclear
envelope
Plasma
membrane
Nucleolus

11. S Phase
Synthesis Phase
There is an active synthesis
of histones
Genetic material of each
chromosome is replicated
Centrioles Chromatin
Nuclear
envelope
Plasma
membrane
Nucleolus

12. ??????
�Phase
Second Gap
Start of mitotic spindle
formation
Chromatin fiber starts to
fold to form a chromosome
Forming mitotic spindle Centrioles
Chromosome,
consisting of two
sister chromatids
Centromere

13. M Phase
Cell division proper
Dividing phase
It is a multistep process for
the formation of two new
identical daughter cells
Can be divided into two
types

14. Cell Division
Meiosis Mitosis

15. ??????
??????Phase
Cells in ??????
?????? phase are not actively preparing to
divide
There has to be an external signal to trigger the
onset of first gap phase

16. Cell Division: Mitosis

17. Mitosis
Also known as karyokinesis
Divided into a series of
phases: PMAT

18. Prophase
Chromatin condenses to form chromosomes
Chromosomes thickened and become shortened
Centrioles are duplicated
Nuclear envelope breaks down

19. Prophase
Forming
mitotic
spindle
Centrioles
Chromosome,
consisting of two
sister chromatids
Centromere
Fragments of
nuclear envelope
Spindle
pole
Spindle
microtubules
Centromere

20. Metaphase
Centrioles are on the
opposite ends of the nucleus
nuclear envelope is
completely absent
Chromosomes are
completely attached to the
spindle fibers and move
toward the equator
Metaphase plate
Sister chromatids
Spindle

21. Metaphase
Metaphase plate
Sister chromatids
Spindle

22. Anaphase
Sister chromatids start to
separate
Two identical sets of
chromosomes move toward
the opposite poles
Spindle fibers begins to
disappear
Daughter
chromosomes

23. Telophase
Chromosomes in there
respective poles
becomes enclosed in a
nuclear membrane
Nuclear membrane
forms
Start of cytokinesis
Nucleolus
forming
Cleavage
furrow
Nuclear
envelope
forming

24. Cytokinesis
The cytoplasm of the cell split into two, making
two new cells
pinch the cells into two parts

25. Cell Division: Meiosis

26. Meiosis
Type of cell division in which the chromosomes
number of the daughter cell is reduced into half
Composed of two successive cell division

27. Meiosis
Meiosis II Meiosis I
Reduction Division
Homologous Chromosomes
come in pair
Composed of four (4) stages

Equational Division
Sister chromatids of each
chromosomes separate
leading to the formation of
four (4) mature sex cells
Composed of four (4) stages

28. Prophase I
There are five events taking place in this phase
L Z P D D

29. Leptotene
Almost similar
to the early
stage of
prophase in
mitosis
Zygotene
Synapsis
occurs
forming
TETRADS
Pachytene
Crossing over
Diplotene
Disintegration
of nuclear
envelope
Diakinesis
Formation of
spindle fibers
Spindle fibers
starts to be
attached to
the tetrads

31. Metaphase I
Nuclear membrane
completely disintegrated
Spindle fibers are now
completely attached to the
tetrads
Tetrads move to the
metaphase plate

32. Anaphase I
Chromosomes move from
the center of the cell to the
opposite poles

33. Telophase I
Cytoplasm divide and the
nuclear membrane is formed

34. Cytokinesis I
The cytoplasm of the cell split into two, making
two new cells (46n)

35. Prophase II
Similar to the mitotic prophase except that it
contains haploid chromosomes

36. Metaphase II
Formation of spindle fibers
Chromosomes aligned at the metaphase plate

37. Anaphase II
Daughter chromosomes move toward the
opposite poles

38. Telophase II
Reappearance of nuclear envelope
Formation of four (4) haploid daughter cells

39. Cytokinesis II
The cytoplasm of the cell split into two, making
four new cells (23n)