2. Walter Flemming (1879) studied
mitosis for the first time in
erythroblasts and epithelial cells
of Salamander. He coined the
term mitosis.
Mitotic division results in
genetically identical eukaryotic
cells (a clone)
Mitosis is the basis of asexual
reproduction .
Mitosis is a part of well ordered
scheme of events called the
cell cycle.
Mitosis
3. • It is a series of changes that
occur during growth and
division of the cell to form two
daughter cells.
• Interphase occupies 75-90%
of the total generation time.
• It prepares the nucleus and
the cell to divide.
• Interphase is also known as
intermitosis.
• Mitosis and cytokinesis
makes the M phase.
Cell cycle
4. Phases of the cell
cycle: • G1- phase: cell grows in size,
nucleus enlarges slightly.
RNAs and proteins are
synthesized.
• S- phase: phase of DNA
replication.
• G2- phase: RNA and protein
synthesis continues.
Macromolecules are formed
for multiplication of cell
organelles, spindle
formation and cell growth.
5. The cell nucleus is well
defined and bounded by
the nuclear envelope.
Two pairs of centrioles.
Chromosomes have
duplicated, but cannot be
distinguished individually,
indistinct mass of
chromatin.
Interphase
6. Prophase:
•Changes occurs in both the nucleus and the
cytoplasm.
•The Nucleolus and nuclear envelope
disappears.
•The chromatin fibers are more tightly coiled.
•Chromatin condense and visible as set of
sister chromatids.
•Sister chromatids joined by centromere.
•Spindle appears, made up of microtubules
and proteins.
•Around each centriole pair , microtubules
forms in a radial array, called an aster.
7. Metaphase
Centriole pairs are now at opposite
poles of the cell.
mitotic spindle complete.
Chromatid sets move to spindle
equator.
The chromosomes lie with their long
axes at roughly right angles to the
spindle axis.
Kinetochores present in the
centromere.
Kinetochores interact with the polar
fibers of spindle, throwing the
chromosomes in agitated motion.
8. Anaphase
The paired centromeres
of each chromosome move
apart, librating the sister
chromatids from each other.
sister chromatids from
individual chromosomes
moving to opposite poles of
the spindle.
9. Telophase
two new nuclei form at the two poles
of the cell where the chromosomes
gathered.
Separation of chromosomes
completed.
Division of cytoplasm begins.
Nucleus & nucleolus reform
Chromatin fibers of Chromosomes
uncoil.
Mitosis , the equal division of
nucleus into 2 genetically identical
10. Cytokinesis
•The division of cytoplasm is
usually well under way by this
time.
• Microfilaments constrict cell
at equator pinching it in two.
Cell Plate forms (plants)
Cleavage furrow
forms(animals).
• Forms two, identical
daughter cells
11. Plant Animal
• Plant cells undergo cytokinesis by forming a cell
plate between the two daughter nuclei
• Animal cells undergo cytokinesis through the
formation of a cleavage furrow. A ring of
microtubules contract, pinching the cell in half.
12. Cytokinesis (in animal cells)
• In animal cells, it occurs by a
process known as cleavage.
• The Ist sign is the appearance of a
cleavage furrow, which begins as a
shallow groove in the cell surface.
• On the cytoplasmic side of the furrow
is a contractile ring of microfilaments
made of the protein actin.
• As the dividing cell’s ring of
microfilaments contracts its diameter
shrinks.
• The cleavage furrow deepens until
the parent cell is pinched into two.
13. Cytokinesis (in plant cells)
• Cytokinesis in plant cells, which have walls is
different.
• There is no cleavage furrows.
• Instead a structure called cell plate forms
across the midline of the parent cell.
• The cell plate forms from the fusion of
membrane vesicles derived from Golgi
complex.
• As the vesicles fuse, a double membrane
forms.
• The fusion of each of these two membranes
15. Significance of mitosis
1. Growth and development: somatic cells are
formed by mitosis. Therefore mitosis is
essential for growth and development of a
multicellular organism.
2. Maintenance of chromosome number:
mitosis is accompanied by replication and
equitable distribution of chromosomes so cells
have same number and type of chromosome.
3. Replacement: it is a mechanism for old or
worn out cells.
4. Asexual reproduction: mitosis is involved in
asexual reproduction and regeneration.
