Life sciences
(

Miss Cybil N. Khumalo
University of Johannesburg
201212375@student.uj.ac.za
CHROMOSOMES
 Chromosomes form when the chromatin network in the nucleus of
the cell, coil up, shortens and thickens.
 Ea...
CHROMOSOME
STRUCTURE

X and Y chromosomes:
gonosomes/sexchromosomes

Colored bands
represents
different genes
THE PHASES OF THE CELL CYCLE
The cell cycle includes the following phases:
 Interphase (include G1- , S- [DNA synthesis] ...
Why is Mitosis
important?
Allow an organism to
grow.
Repairs damaged
cells/tissue.
Replace dead cells/tissue.

Reprodu...
Where does Mitosis take place?
 In all somatic cells (include all body cells and
excludes the sex cells – sperm/egg cells...
The process of Mitosis.

 CONSIST OF A FEW PHASES:
 INTERPHASE
 PROPHASE
 METAPHASE
 ANAPHASE
 TELOPHASE
INTERPHASE
 Cell builds up enough energy for division
process.
 DNA replication occurs
 Cell look normal, like before d...
PROPHASE
 Nuclear envelope and nucleolus
disappear.
 Chromatin become more tightly
coiled, and condenses into
individual...
METAPHASE
 The centrioli reached the opposite poles
with the spindle fibers in between.
 The chromosomes arrange randoml...
ANAPHASE
 The spindle fibers pull tight.
 The centromers attaching the
chromatids of the chromosomes split in
half.
 Da...
EARLY TELOPHASE – KARYOKINESIS
(DIVISION OF NUCLEUS

 Daughter chromosomes reach poles.

 Nuclear envelope surrounds
chr...
LATE TELOPHASE – CYTOKINESIS
(DIVISION OF THE CYTOPLASM)
 Invagination of the cytoplasm and plasma
membrane occurs. (Clea...
MITOSIS PROCESS
CANCER

 Cancer is caused by the loss of cell cycle controls in
cancer cells.

 Cancer cells usually continue to divide ...
Ovarian cancer cells
Breast tumor

Ovarian cancer
cells dividing
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mitosis- cell division

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Biology: mitosis, a cell division process

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mitosis- cell division

  1. 1. Life sciences ( Miss Cybil N. Khumalo University of Johannesburg 201212375@student.uj.ac.za
  2. 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. 3. CHROMOSOME STRUCTURE X and Y chromosomes: gonosomes/sexchromosomes Colored bands represents different genes
  4. 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. 5. Why is Mitosis important? Allow an organism to grow. Repairs damaged cells/tissue. Replace dead cells/tissue. Reproduction in some simple organisms.
  6. 6. Where does Mitosis take place?  In all somatic cells (include all body cells and excludes the sex cells – sperm/egg cells)
  7. 7. The process of Mitosis.  CONSIST OF A FEW PHASES:  INTERPHASE  PROPHASE  METAPHASE  ANAPHASE  TELOPHASE
  8. 8. INTERPHASE  Cell builds up enough energy for division process.  DNA replication occurs  Cell look normal, like before division
  9. 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. 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. 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. 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. 13. 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)
  14. 14. MITOSIS PROCESS
  15. 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 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. (information from Campbell & Reece, Biology: 2010)
  16. 16. Ovarian cancer cells Breast tumor Ovarian cancer cells dividing
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