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Stages of Biology a programmed instruction.

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  1. 1. Stages of Mitosis Alafiya Taher Kapadia
  2. 2. 1. Why do cells divide? 2. How do cells divide? 3. Stages of Mitosis a) Interphase b) Prophase c) Metaphase d) Anaphase e) Telophase f) Cytokinesis Index
  3. 3. Biology is the only subject in which multiplication is the same thing as division…
  4. 4. You started as a cell smaller than a period at the end of a sentence… • Where it all began…
  5. 5. • And now look at you… How did you get from there to here?
  6. 6.  Going from egg to baby…. the original fertilized egg has to divide… and divide… and divide… and divide… • Getting from there to here…
  7. 7.  For reproduction  For growth  from fertilized egg to multi-celled organism  For repair & renewal  replace cells that die from normal wear & tear or from injury • Why do cells divide?
  8. 8. •Pop quiz 1.What is the importance of cell division? Growth Death Cancer
  9. 9. Mitosis is the division of somatic cells (body cells) It is the process in which the nucleus divides to form two new nuclei. The chromosomal number remains unchanged. •How do cells divide? Somatic Cell Daughter Cells
  10. 10. •Pop quiz 1. Mitosis in body cells results in _____________. 4 daughter cells 2 daughter cells 1dupilcate cell
  11. 11. • The process of mitosis is fast and highly complex. The sequence of events is divided into stages corresponding to the completion of one set of activities and the start of the next. These stages in order of occurrence are- • Interphase • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis •Stages of Mitosis
  12. 12. •Pop quiz 1. The order of the stages in Mitosis is Interphase-Anaphase-Telophase- Prophase-Metaphase Interphase-Prophase-Metaphase- Anaphase-Telophase Interphase-Metaphase-Anaphase- Prophase-Telophase
  13. 13. • The cell is in Interphase for most of its life cycle. • In Interphase, the cell “prepares” for division by • obtaining nutrients and growing, • copying its DNA, and • replicating its centrioles. • The nuclear membrane is still visible. • Chromatin has not yet condensed into chromosomes in this stage. • The nucleolus is still present. •Interphase chromatin threads nucleolus centrioles
  14. 14. •Pop quiz 1. Body cells are in ________________ stage for most of its life cycle. Anaphase Interphase Prophase
  15. 15. •Pop quiz 1. Body cells are in ________________ stage for most of its life cycle. Anaphase Interphase Prophase
  16. 16. • In Prophase:- • DNA becomes visible as chromosomes • Nuclear membrane dissolves • Centrioles migrate to opposite poles • Spindle fibers form •Prophase chromatids centrioles spindle fibers nucleus
  17. 17. •Pop quiz 1. Spindle fibers form in __________ stage. Anaphase Prophase Metaphase
  18. 18. In Metaphase:- • Spindle fibers attach to centromeres • Chromosomes line up at midline of the cell • This organization helps to ensure that in the next phase, when the chromosomes are separated, each new nucleus will receive only one copy of each chromosome. •Metaphase equatorial plane centromeres
  19. 19. •Pop quiz 1. In Metaphase chromosomes line up along the _________ Equatorial Plane Poles Don’t line up
  20. 20. • In anaphase, the spindle fibres shorten, which splits the chromosome strand into two separate, sister chromatids. The sister chromatids are pulled to opposite ends of the cell. • This is the only stage in the life of a cell where the chromosome number is greater than a 2n (or diploid) count •Anaphase sister chromatids
  21. 21. •Pop quiz 1. Only stage where chromosomal number is greater than 2n is ___________ Metaphase Anaphase Telophase
  22. 22. • The chromosomes finally reach opposite poles (the ends) of the cell. • The nuclear envelope and nucleolus reform around each new set of chromosomes. The chromosomes disperse and are no longer visible. • Spindle fibers disperse and are no longer visible. •Telophase nuclear envelope cytoplasm begins to divide
  23. 23. • Cytokinesis marks the end of mitosis in the cell cycle. It is where the cell officially splits into two separate cells, called daughter cells. Each daughter cell now has the same number of chromosomes as the original cell before mitosis. The cell splits when a furrow forms that pinches the cell in two. •Cytokinesis contractile ring centrosome nuclear envelope decondensed chromosome
  24. 24. •Pop quiz 1.The chromosome reach the poles of the cell in ___________ stage. Prophase Anaphase Telophase
  25. 25. • Prophase: • Chromosomes condense • Nuclear envelope disappears • centrosomes move to opposite sides of the cell • Spindle forms and attaches to centromeres on the chromosomes • Metaphase • Chromosomes lined up on equator of spindle • centrosomes at opposite ends of cell • Anaphase • Centromeres divide: each 2-chromatid chromosome becomes two 1-chromatid chromosomes • Chromosomes pulled to opposite poles by the spindle • Telophase • Chromosomes de-condense • Nuclear envelope reappears • Cytokinesis: the cytoplasm is divided into 2 cells Exit • Summary of Mitosis