1. The document discusses cell division through mitosis and meiosis. 2. Mitosis produces two identical daughter cells through the four stages of prophase, metaphase, anaphase and telophase. This ensures new cells are identical to the parent cell. 3. Meiosis produces four non-identical daughter cells through two cell divisions. It reduces the chromosome number by half and introduces genetic variation.

1. 1 © Gabriel Chua, 2013
Chapter 5: Cell Division
Important terms and concept
1. Haploid – Cell with single set of chromosome (n)
2. Diploid – Cell with complete sets of chromosomes (2n)
3. Cell division:
a) Mitosis – 1 parent cell (2n)  2 identical daughter cells ( 2n )
b) Meiosis – 1 parent cell (2n)  4 different daughter cells ( n )
4.
5.1) Mitosis
1. 1 parent cell (2n)  2 identical daughter cells ( 2n )
2. It is part of the cell cycle (Interphase  Mitosis  Cytokinesis)
3. Interphase is divided into:
a) G1 phase  Growth of cell by producing proteins and organelles
b) S phase  Synthesis / duplication of DNA (thread-like chromatin)
c) G2 phase  Growth of cell by producing proteins and organelles
4. Mitosis is divided into prophase, metaphase, anaphase and telophase
chromatid sister chromatid
chromosome chromosome
homologous chromosome

2. 2 © Gabriel Chua, 2013
Prophase  Chromosomes start to appear and condense as 2
identical chromatids
 Nuclear membrane disintegrate and nucleolus
disappear
 Centrioles move apart to opposite sides
 Spindle fibre begins to form
Metaphase  Chromosomes move to cell’s equator
 Chromosomes line up at cell’s equator with centromeres
attached to spindle fibre
 Each chromatid faces its own pole
Anaphase  Chromosomes divide into two
 Each sister chromatid separate and move to opposite
poles
 When the chromatids reached its own pole, they become
independent chromosomes
Telophase  There are now 2 sets of chromosomes, one at each pole
 Chromosomes become thread-like structures
 Spindle fibre disappear
 Nuclear membrane begins to form around both sets of
chromosomes
 Nucleolus reappears
 Cytokinesis begins
5. Cytokinesis in animal cells is by forming cleavage while that of plant cells is by forming
cell plate.
6. Importance of mitosis
a) Repair damaged cells and replace dead cells
b) Asexual reproduction in unicellular organisms
c) Preserve diploid number of chromosome
d) Ensure new cells are identical to parent cells

3. 3 © Gabriel Chua, 2013
7. Application of mitosis
a) Repair damaged cells and replace dead cells
b) Tissue culture
c) Clonnnig
d) Uncontrolled mitosis causes cancer
5.2) Meiosis
1. 1 parent cell (2n)  4 different daughter cells ( n )
2. Meiosis is divided into:
a) Meiosis I b) Meiosis II
 Prophase I  Prophase II
 Metaphase I  Metaphase II
 Anaphase I  Anaphase II
 Telophase I  Telophase II
Prophase I  Chromosomes thickens and condense
 Each chromosome consists of 2 sister chromatids
 Homologous chromosomes pair together (bivalent) via
synapsis
 The criss-cross between homologous chromosomes is
known as chiasmata
 This results in genetic variation
 Centrioles move to opposite poles
 Spindle fibre forms
 Nuclear membrane and nucleolus disintegrate
Metaphase I  Paired homologous chromosomes line up at cell’s
equator
 Each chromosome are attached to spindle fibre at
centromeres
 Each chromosome faces its own pole
Anaphase I  Paired homologous chromosomes separate from each
other and move to opposite pole

4. 4 © Gabriel Chua, 2013
Telophase I  Chromosomes reached its own pole
 Each pole has haploid chromosome set
 Spindle fibre disappear
 Nuclear membrane and nucleolus reform
 Cytokinesis begins
3. Meiosis II is the same as mitosis
4. Importance of meiosis
a) Allow trait inheritance in offspring
b) Maintain same number of chromosomes in each generation
c) Ensure production of haploid gametes in sexual reproduction
d) Produce genetic variation
Comparison between Meiosis I and Meiosis II
Meiosis I Meiosis II
Similarities
1. Consists of 4 stages, ie. prophase, metaphase, anaphase & telophase
2. Involves division of nucleus and cytoplasm
Differences
Yes, at Prophase I Synapsis No
Yes, at Prophase I Crossing over No
In metaphase I, paired
homologous chromosomes /
bivalent / tetrad line up at
equator
Metaphase
In metaphase II, sister
chromatids line up at equator
In anaphase I, homologous
chromosomes separate and
move to opposite side
Anaphase I
In anaphase II, sister
chromatids separate and
move to opposite side
2 different daughter cells ( n )
Number of daughter cells
4 different daughter cells ( n )

5. 5 © Gabriel Chua, 2013
Comparison between Meiosis and Mitosis
Meiosis Mitosis
Similarities
1. Both process are cell division process
2. Chromosomes only replicate once
Differences
Reproductive cells Place occur Somatic cells
Parent cells divide twice Number of division Parent cells divide once
4 different daughter cells (n) Number of daughter cells 2 identical daughter cells
(2n)
Yes, at Prophase I Synapsis No
2 Number of cytokinesis 1
Yes, at Prophase I Crossing over No
Each daughter cell has half
the number of chromosome
of parent cell
Number of chromosomes in
daughter cells
Each daughter cell has the
complete number of
chromosome as parent cell
Genetic composition are
different to parent cell or to
each other
Genetic composition of
daughter cells
Genetic composition are
identical to parent cell and
each other
Occurs during interphase
before Meiosis I begins DNA replication
Occurs during interphase
before mitosis begins
 Produce gametes
 Cause genetic variation
 Reduce number of
chromosomes to half
Role in animal body
 Produce cells for
growth
 Asexual reproduction