grade 10 life sciences mitosis slides

1. GRADE 10 LIFE SCIENCES
MITOSIS
PRESENTED BY PHINDILE NTULI

3. UNIT 3:
CELL DIVISION (MITOSIS)

4. CHROMOSOMES

5.  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.

6. CHROMOSOME
STRUCTURE

7. X andY chromosomes:
gonosomes/sex-
chromosomes

8. 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.

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

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

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

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

13. 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.

14. 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.

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

16. TELOPHASE
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

17. 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

18. LATE TELOPHASE – CYTOKINESIS
(DIVISION OF THE CYTOPLASM)
 Invagination of the cytoplasm and plasma
membrane occurs. (Cleavage furrow 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)

19. MITOSIS PROCESS