Life Sciences Grade 10

1. Cell Division: Mitosis
By Marry Ramaisela Matseba

2. CHROMOSOMES
 Chromosomes form when the chromatin network in the nucleus of
the cell, coil up, shortens and thickens.
 Each organism has a specific amount of chromosomes.
 All humans have 46 chromosomes.
 These chromosomes are arranged in identical pairs called
homologous chromosome pairs –
 Therefore humans have 23 homologous pairs of chromosomes.
 These chromosomes is only visible during cell division processes.
 One chromosome consist of 2 chromatids and one centromere
that attach the chromatids together.
 Each chromatid consist of genes which in turn consist of DNA.

3. CHROMOSOME
STRUCTURE

4. THE PHASES OF THE CELL CYCLE
The cell cycle includes the following phases:
 Interphase (include G1- , S- [DNA synthesis] and G2
phase)
 Mitosis
 Cytokinesis
 Growth
The result is 2 identical cells.

5. Why is Mitosis important?
 Allow an organism to grow.
 Repairs damaged cells/tissue.
 Replace dead cells/tissue.
 Reproduction in some simple organisms.

6. Where does Mitosis take place?
 In all somatic cells (include all body cells and excludes the
sex cells – sperm/egg cells)

7. The process of Mitosis.
 CONSIST OF A FEW PHASES:
 INTERPHASE
 PROPHASE
 METAPHASE
 ANAPHASE
 TELOPHASE

8. INTERPHASE
 Cell builds up enough energy for division process.
 DNA replication occurs
 Cell look normal, like before division

9. PROPHASE
 Nuclear envelope and nucleolus disappear.
 Chromatin become more tightly coiled, and condenses into
individual chromosomes. Chromosomes arrange randomly
in the cell.
 Centrioli move to opposite poles, with spindle fibers
stretching between them.

10. METAPHASE
 The centrioli reached the opposite poles with the spindle
fibers in between.
 The chromosomes arrange randomly on the equator, each
single chromosome attaching to a separate spindle fiber by
means of the centromere.

11. ANAPHASE
 The spindle fibers pull tight.
 The centromers attaching the chromatids of the
chromosomes split in half.
 Daughter chromosomes move to opposite poles.

12. EARLY TELOPHASE – KARYOKINESIS
(DIVISION OF NUCLEUS
 Daughter chromosomes reach poles.
 Nuclear envelope surrounds chromosomes.
 Nucleolus reappear at each pole.
 Chromosomes become less condense forming chromatin.
 Two identical nuclei has been formed

13. LATE TELOPHASE – CYTOKINESIS
(DIVISION OF THE CYTOPLASM)
 forms in animal cells and a cytoplasmic plate forms in plant
cells)
 Continues until the cell in divided into 2 separate cells.
(Identical to one another and to the original cell)
 Invagination of the cytoplasm and plasma membrane
occurs. (Cleavage furrow

14. MITOSIS PROCESS

15. CANCER
 Cancer is caused by the loss of cell cycle controls in
cancer cells.
 Cancer cells usually continue to divide well beyond a
single layer, forming a clump of overlapping cells called a
tumor.
 Malignant tumors invade surrounding tissues and can
metastasize (spread) exporting cancer cells to other parts
of the body, where they may form secondary tumors.
 They do not exhibit anchorage dependence or density
dependent inhibition.

16. Types of Cancer
Ovarian cancer cells Breast tumor

17. References
 Bio Review Cell Division
http://library.thinkquest.org/28751/review/4.html.Access
 Molecular Expressions
http://micro.magnet.fsu.edu/micro/gallery/mitosis/mitosis.html
 University of North Carolina at Charlotte
http://www.bioweb.uncc.edu/biol1110/stages.htm
SlideShare References
 Farrellw (2012)Mitosis powerpoint .Available from
slideshare at https://www.slideshare.net/farrellw/mitosis-
powerpoint-11179257 (Accessed 18 September 2017)

18.  Patterson,C(2008)Cell Division Mitosis and Meiosis .Available
from slideshare at
https://www.slideshare.net/cathrinepatterson/cell-division-mitosis-
and-meiosis-presentation
 Sherif,S.(2011)Cell cycle & cell division .Available from
slideshare at https://www.slideshare.net/shimaasherif/cell-cycle-
cell-division
 Stratton,L.(2015) 2015 Mitosis.Available from slideshare at
https://www.slideshare.net/stratt45/2015-mitosis (Accessed 18
September 2017)

19.  Mthambo,G.(2014)Mitosis:Life Science For Grade
10’S.Available from slideshare at
https://www.slideshare.net/201224785/mitosis-life-
sciences-for-grade-10s (Accessed 18 September 2017)
 Taylor,S(2009)Cell Division-Mitosis.Available from
slideshare at https://www.slideshare.net/gurustrip/cell-
division-mitosis-2630874