Mitosis is the process of cell division that results in two daughter cells with identical genetic material to the original parent cell. It has four main stages: prophase, metaphase, anaphase and telophase. Cytokinesis then divides the cytoplasm. In animal cells, cytokinesis occurs via cleavage furrow formation, while in plant cells it occurs through cell plate formation between the daughter cells. Mitosis plays important roles in growth, cell replacement, regeneration, and asexual reproduction.

1. 12.3 MITOSIS
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2. OBJECTIVES
At the end of this lesson, students should be
able to:
Describe the four stages of the mitotic cell
division
Explain the behaviour of the chromosomes
at each stage
Describe briefly the cytokinesis process
Compare the cell division in animal and plant
State the significance of mitosis.
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3. MITOSIS
• Mitosis Process
- one part of the cell cycle
- involves two phases: nucleus division
(karyokinesis) & cytoplasm division
(cytokinesis).
- divided into four distinct stages:
prophase, metaphase, anaphase &
telophase.
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4. With the exception
1. Prophase of higher plant cells
-chromosomes become which lack them,
visible as long, thin
tangled threads. the centrioles
-Gradually they shorten migrate to opposite
and thicken, & each is ends of poles of the
seem to comprise two
chromatids joined at the cell.
centromere.
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5. 5

6. • From each centriole, microtubules
develop and form a star-shaped
structure called an aster.
• Some of these microtubule, called
spindle fibers, span the cell from pole
to pole.
• form the spindle.
• The nucleolus disappears and finally
the nuclear envelope disintegrates,
leaving the chromosomes within the
cytoplasm of the cell. 6

7. 2. Metaphase
- The chromosomes
arranged themselves at
the centre of equator
of the spindle, and
become attached to
certain spindle fibers at
the centromere.
- Contraction of these
fibers draws the
individual chromatids
slightly apart. 7

8. Anaphase The
- centromeres shorting of
split and
further the spindle
shortening of fibers is due
the kinetochore to the
microtubules
causes the two
progressive
chromatids of removal of
each the tubulin
chromosome to molecules of
separate and
migrate to which they
opposite poles. are made. 8

9. • Microtubules attached at centromere;
centromere move first
• Nonkinetochore microtubules
lengthen; poles of cell move farther
apart
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10. 1.Telophase
- chromatids reach their
respective poles and a new
nuclear envelope forms
around each group.
- chromatids uncoil and
lengthen, - invisible again.
- spindle fibers disintegrate
and nucleolus reforms in
each new nucleus.
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11. Cytokinesis – division of
cytoplasm
1. In Animal Cells
• Occur by a process
known as cleavage.
• first sign of
cleavage is the
appearance of
cleavage furrow.
(Begins as a shallow
growth in the cell
surface)
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12. • On cytoplasmic side- is a
contractile ring of actin
microfilaments associated with
myosin
• Causing ring to contract
• Cleavage furrow deepens until
parent cell pinched in two
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13. Cytokinesis
1. In Plant Cells
• Have walls
• During telophase, vesicles derived from
Golgi apparatus move along microtubules
to the middle of the cell, unite, producing
a cell plate.
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14. • Cell wall material
carried in the
vesicles collect in
the cell plate as it
grows
• The cell plate
enlarges until its
surrounding
membrane fuses
with the plasma
membrane
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15. • Two daughter cells result, each
with its own plasma membrane.
• A new cell wall arising from the
contents of the cell plate has
formed between the daughter cells.
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16. Mitosis in a generalized animal cell.
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17. Mitosis in a generalized animal cell.
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18. Differences between mitosis in plant
and animal cells
Animal Cells Plant Cells
 Involve aster or 1. lack of centriols.
spindle formation.
 Cytokinesis occurs  Occurs by the
by the constriction of growth of a cell plate
microtubules – through the fusion of
cleavage furrow. vesicles.
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19. Significance of mitosis
1. Genetic stability
• same number of chromosomes as the
parent cell.
• Daughter cells are genetically identical
to the parent cell and no variation in
genetic information
• This result in genetic stability within
populations of cells derived from the
same parental cells.
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20. 2. Growth
• The number of cell within organism
increases
- basis of growth in multicellular
organisms.
3. Cell replacement
• Replacement of damaged cells and
tissues
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21. 4. Regeneration
Some animal are able to regenerate
whole parts of the body, such as legs in
crustacea and arms in star fish.
5. Asexual reproduction
production of new individuals of a
species by one parent organism.
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