Continuation of the cell structure and function. This presentation highlights the cell cycle and concentrate on how cell division occur and the steps involved in cell dividing. 2018/2019

1. THE CELL CYCLE AND CELL DIVISION
Presented by:
Fasama Hilton Kollie
Lecturer, Department of Biology
Mother Patern College of Health Sciences

2. CHAPTER OUTLINE
1. Cell Division
2. Importance of Cell Division
3. Prokaryotic and Eukaryotic Cell Division
4. Cell Cycle
5. Regulation of the Cell Cycle

3. LESSON OBJECTIVES
• By the end of this session, the learners will be able to;
1. Define cell division and cell cycle
2. Identify the purpose of cell division
3. Describe cell division in prokaryotic and Eukaryotic
cell
4. Describe the cell cycle

4. CELL DIVISION
• It’s the process by which a cell divides to form two new
cells
• Three types of cell division or cell reproduction in
organism
• Prokaryotes (bacteria)
— Binary fission
• Divides forming two new identical cells

5.  Eukaryotes
— Mitosis
• Cell or organism growth
• Replacement or repair of damaged cells
— Meiosis
• formation of sex cells, or gametes

6. WHY DO CELLS DIVIDE?
• Cells divide for growth, development, repair of worn-out tissues
and reproduction
• To facilitate the exchange of materials
• To control DNA overloading

7. PROKARYOTIC CELL DIVISION
1. Binary Fission
• Three (3) major steps;
• DNA Replication
DNA is copied resulting into two identical chromosomes
• Chromosome Segregation
Chromosomes separate and move towards ends (poles) of cell
• Cytokinesis (Separation)
Cytoplasm divides forming two (2) cells
• Each new daughter cell is Genetically Identical to parent cell

8. Prokaryotic Cell
Division

9. EUKARYOTIC CELL DIVISION
• Cell division that results in two daughter cells each having the same
number and kind of chromosomes as the parent cell
1. MITOSIS
• Two (2) main steps:
1. Mitosis
Fours steps; [Prophase>Metaphase>Anaphase>Telophase]
2. Cytokinesis
Cytoplasm divides forming two new daughter cells
• Each daughter cell is Genetically Identical to parent cell

11. Eukaryotic Cell Division Cont.
• Cell division that results in four daughter cells
2. MEIOSIS
• Two (2) major steps:
1. Mitosis
Fours steps; [Prophase>Metaphase>Anaphase>Telophase]
2. Cytokinesis
Cytoplasm divides forming two new daughter cells
• Each daughter cell is NOT Genetically Identical to parent cell

12. CELL CYCLE

13. THE CELL CYCLE
• The sequence of events from the time a cell first arises as a result of cell division
until the time when that cell itself divides.
• Arise – Divide
• This consist of periods of;
•Growth and Development
•DNA Replication
•Preparation For Division
•Cell Division
• Cell after division begins a new cycle

14. The Cell Cycle
• Consist of two(2) main
periods;
I. Interphase
II. Mitotic Phase M phase
G2
phase
S
phase
G1 phase

15. CELL CYCLE - Interphase
• Interphase: period of growth and DNA
replication between cell divisions
• Three (3) phases:
• G1 Phase
‒ Cell increases in size
• S Phase
‒ Replication of DNA
‒ Two sister strands of DNA called chromatids
are produced
• G2 Phase
‒ Organelles double
‒ New cytoplasm forms
‒ All other structures needed for mitosis form
Centrioles
Nuclear membrane
Nucleolus
Chromosomes

17. M phase
G2 phase
S phase
G1 phase
CELL CYCLE

18. CELL CYCLE – Mitotic Phase
• Mitotic phase is the stage when a cell divides
• Mitosis – the division of a single nucleus into two genetically
identical daughter nuclei
• This division involves two(2) processes;
‒ Division of the nucleus
‒ Separation of the cytoplasm and the new nuclei into daughter cells

19. Mitotic Phase
• Divided into two (2) mitotic phases
• 1st MP contain four stages (P-MAT)
‒ Prophase, metaphase, anaphase and telophase
• 2nd MP is cytokinesis

20. 1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
•P-MAT
Interphase 1 2
3
4
Cytokinesis
Mitosis

21. Interphase:
Centrioles
Nuclear membrane
Nucleolus
Chromatids

22. Early Prophase:
• Chromatids condense becoming
chromosomes
• Nucleolus disappears
• Centrioles separate and start moving
to opposite ends of the cell
• Spindle begins to form
Chromatids
connected by a
centromere.
Centrioles
Spindle made of
microtubules

23. Late Prophase:
• The nuclear membrane
fragments and the
microtubules invade the
nuclear area
• Centrioles have moved to the
opposite poles
• The spindle is completely
formed
centrioles
Microtubules
form a complete
spindle
chromatids
centrioles

24. Metaphase:
In metaphase;
• The chromosomes are aligned
at the metaphase plate
• Centrioles move at polar ends
and projects spindle fibers to
connect each chromosome
Centrioles
Chromosomes
Spindle
composed of
microtubules

25. Anaphase:
In anaphase;
• The paired chromosomes
(sister chromatids) separate
• Separated chromatids move
to opposite pole
• Partial division of cytoplasm
begins
Chromatids are
being pulled to
opposite sides of
the cell.
Shortening of the
microtubules

26. Telophase:
In telophase;
• Chromosomes are at the
poles
• Chromosomes uncoil-turn
chromatin
• Nuclear envelops reforms
• Spindle fiber disappear
Nuclear
membrane
is returning

27. Cells return to interphase
Cytokinesis:
• Occurs at the end of mitosis
• Animal cells: a cleavage furrow
separates the daughter cells
• Plant cell: a cell plate separates the
daughter cells
• Daughter cells are genetically
identical

28. Mitosis
Animation

29. 1. Name the phases
starting at the top.
Mitosis
SELF QUIZ
Design an Education Game from Here
A
B
C
D
E

30. Name the phases:
1. Identify W
Sister Chromatid
2. Identify X
Spindle fibre
3. Identify Y
Centriole
4. Identify Z
Centromere
SELF QUIZ
z
w

31. Name this phase
and provide brief
description
Telophase

32. CONTROL OF THE CELL CYCLE
• Regulatory proteins called cyclins control the cell cycle at
checkpoints:
• G1 Checkpoint—decides whether or not cell will divide
• S Checkpoint—determines if DNA has been properly replicated
• Mitotic Spindle Checkpoint—ensures chromosomes are aligned at
mitotic plate

33. REFERENCE
• Nabor, Murray W., INTRODUCTION TO BOTANY. Copyright 2004 Pearson
Education, Inc., Publilshing as Benjamin Cummings, 1301 Sansome St., San
Francisco, CA 94111.
www.aw-bc.com
• CK – 12
https://www.ck12.org/biology/cell-division/lesson/Cell-Division-BIO/
• Image Attributions
[Prokaryotic cell division]
Credit: Mariana Ruiz Villarreal (LadyofHats) for CK-12 Foundation
Source: CK-12 Foundation
License: CC BY-NC 3.0