Cell division functions to produce new cells for reproduction, growth, and repair. It involves the distribution of identical genetic material, DNA, to two daughter cells. The cell cycle consists of interphase and mitosis. Interphase involves cell growth and DNA replication. Mitosis distributes identical DNA to two daughter cells through the stages of prophase, metaphase, anaphase, and telophase. Cytokinesis then divides the cytoplasm, producing two genetically identical daughter cells.

1. Edited by: Hasimah Azit

2. CELL DIVISION FUNCTIONS
IS to:
Produce new cells for:
 reproduction – gamete
 growth – new cells
 and repair – replace dead
cells

3. Basic definitions
 gene - basic unit of heredity; codes for a specific
trait
 somatic cell - all body cells except reproductive
cells
 gamete - reproductive cells (i.e. sperm & eggs)
 chromosome - elongate cellular structure
composed of DNA and protein

4. diploid (2n) - cellular condition where each
chromosome type is represented by two
homologous chromosomes
haploid (n) - cellular condition where each
chromosome type is represented by only one
chromosome
chromatid - one of two duplicated chromosomes
connected at the centromere
centromere - region of chromosome where
microtubules attach during mitosis and meiosis
Basic definitions

5. Cell division involves
 the distribution of identical genetic material,
DNA
 to two daughter’s cells.
2n
2n
2n
two
identical
daughter
cells

6. The Cell Cycle

7. Cell CycleCell Cycle
The dividingdividing and non-dividingnon-dividing stages in the life of a
cell.
Phases:
1.1. InterphaseInterphase: growth and DNA replication
2.2. ProphaseProphase
3.3. MetaphaseMetaphase
4.4. AnaphaseAnaphase
5.5. TelophaseTelophase
6. Cytokinesis –6. Cytokinesis – cytoplasm dividedcytoplasm divided
Mitotic divisionMitotic division

8. InterphaseInterphase
1.1. GG11 (gap) phase:(gap) phase:
a. grow into matured size and protein is synthesized
b. most cell are arrested in this phasemost cell are arrested in this phase.
2.2. S phase:S phase:
a. DNA replicationDNA replication takes place.
3.3. GG22 (gap) phase:(gap) phase:
a. Cellular growth and energy and organelles
preparation for M phaseM phase.

9. MitosisMitosis
The form of cell divisioncell division by which a somaticsomatic
cellcell duplicates.
MitosisMitosis is asexual reproduction.asexual reproduction.
Cell divisionCell division is the continuation of life based
on the reproduction of cells.

10. mitosis - nuclear/chemical events resulting
in two daughter nuclei which
have identical genetic material to
each other and to the mother cell
cytokinesis - division of the cytoplasm.
Mitosis divisionMitosis division

11. Look at the section through the tip of
an onion root tip and try to recognize:
* dividing cells – mitotic cells
* elongated cells

12. Onion root tip
Mitotic cellsElongated cells

14. InterphaseInterphase
NucleusNucleus and nucleolusnucleolus visible.
Nuclear
membrane
nucleolus
cell membrane
chromatin

15. A chromosomechromosome is made up
of a DNADNA
ChromatinChromatin is a long, thin
fiber that is folded and
coiled (invisible).
chromosome

16. Duplication of chromosome – from single strand to double strand

18. Chromosome replicationChromosome replication
A replicated chromosomechromosome consist of two strands
of identical chromosomal material called
chromatidschromatids (sister chromatidssister chromatids).
chromatid
chromatid
S phase: chromosomes replicate
chromosome
chromosome
centromere

19. A chromatidchromatid is a chromatidchromatid as long as it is held in
association with a sistersister chromatidchromatid at the
centromerecentromere.
chromatid
chromatid
centromere
chromosome
ChromatidChromatid

20. ProphaseProphase
Longest phaseLongest phase
Nucleolus disappears
Chromatin material condenses into chromosomeschromosomes,
consisting of two sister chromatidssister chromatids.

21. ProphaseProphase
CentriolesCentrioles move apart (not found in plants).
Spindle fibersSpindle fibers form and attach from centriolescentrioles to
centromerescentromeres
Nuclear envelope fragments and disappears.

22. ProphaseProphase
late prophaselate prophaseearly prophaseearly prophase
centrioles
spindle fibers
centromere
nuclear envelope
disappearing
aster
fibers

23. Find the stages in the picture below

24. MetaphaseMetaphase
Shortest phase
CentriolesCentrioles are at opposite ends of the cell and
attached with aster fibersaster fibers.
ChromosomesChromosomes move to the metaphase platemetaphase plate
(equatorial plateequatorial plate - center of cell).

25. MetaphaseMetaphase
metaphase plate
centrioles
spindle fibers
aster
fibers

26. AnaphaseAnaphase
CentromeresCentromeres uncouple and spindle fibersspindle fibers
shorten.
Sister chromatidsSister chromatids separate and move apart.
After separation, chromatidschromatids are now considered
chromosomeschromosomes.

27. AnaphaseAnaphase
During this phase, the cell contains twice the
normal number of chromosomeschromosomes.
Cell begins to elongateelongate.
At the end, there are equal numbers of
chromosomeschromosomes at the poles.

28. AnaphaseAnaphase
No longer sister chromatidssister chromatids, now chromosomeschromosomes
centriolesspindle fibers
aster
fibers

29. TelophaseTelophase
Cleavage furrowfurrow develops in animal cells
(CytokinesisCytokinesis begins).
Cell plateCell plate develops in plantsplants (no cleavage
furrows in plants).
Nucleolus reappears.
cell plate

30. TelophaseTelophase
Nuclear membrane reappears.
ChromosomesChromosomes uncoil.
In the end, two genetically identical nuclei
(karyokinesiskaryokinesis completed) are present.

31. TelophaseTelophase
cleavage furrow (cytokinesis)
nuclear membrane reforming nucleolus reappears

32. CytokinesisCytokinesis
Cytoplasmic divisionCytoplasmic division
Cell plateCell plate complete in plantsplants
In the end, two separate daughter cells produced
with single nucleus.
cell plate

33. Question:Question:
A cell containing 2020 chromosomeschromosomes at the
beginning of mitosis would, at its completion,
produce cells containing how many
chromosomes eachchromosomes each?

34. Answer:Answer:
20 chromosomes20 chromosomes

35. Question:Question:
A cell containing 4040 chromatidschromatids at the beginning of
mitosis would, at its completion, produce cells
containing how many chromosomes eachchromosomes each?

36. Answer:Answer:
20 chromosomes20 chromosomes

37. What is cancer?
 A cancer cell is a cell that grows out of
control.
 Unlike normal cells, cancer cells ignore signals
to stop dividing, to specialize, or to die and be
shed.
 Growing in an uncontrollable manner and
unable to recognize its own natural boundary,
the cancer cells may spread to areas of the
body where they do not belong.

38. White blood
cells
attack the
cancerous
cell!

39. Find your self:
 How the cancerous cells look
like?
 How these cells affect the
health?
 How these cells spread?
 What causes the cancer in
human?

40. Website for you to visit:
 http://www.cellsalive.com/mitosis.htm
 http://www.biology.arizona.edu/Cell_bio/tuto
rials/cell_cycle/cells 3.html
 http://www.accessexcellence.org/RC/VL/GG/
mitosis.php

http://training.seer.cancer.gov/module_cance
r_disease/unit2_whatscancer3_cell_biology.h
tml