Leading to
Mitosis & Meiosis
by
Muhammad Iqbal Khan
SS Biology
Email ID:mikhan1313@yahoo.com
http://biotech-adventure.okstate.edu/low/basics/mitosis/mitosis-diagram/diagram.gif
Cell Cycle
http://www.bmb.psu.edu/courses/biotc489/notes/cycle.jpg
Mitosis
• One type of cell division
Cell process in which the nucleus
divides to form two nuclei identical to
each other, ...
Mitosis allows for growth
and replaces worn out or
damaged cells.
Interphase
• Period of growth & development
• Hereditary information (DNA)
copied (replicated / duplicated)
• Cells that d...
http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/interphase/interphase.gif
Prophase
•DNA begins to shorten & thicken
–Now called chromatids /
chromosomes
•Centromeres form
•Nuclear membrane breaks ...
http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/prophase/prophase.gif
Metaphase
•Chromatids / chromosomes
line up
•Centromere attaches to
spindle fibers
http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/metaphase/metaphase.gif
Anaphase
•Centromeres divide
•Spindle fibers shorten
•Chromatid pairs separate – move
to ends of cell
•Chromatids are now ...
http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/anaphase/anaphase.gif
Telophase
•Spindle fibers disappear
•Chromosomes uncoil
•Nuclear membrane forms
•Cell divides (cytokinesis)
http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/telophase/telophase.gif
Interphase Prophase
Metaphase Anaphase
Telophase Interphase
http://biology.nebrwesleyan.edu/benham/mitosis/
Mitosis Animation
http://www.johnkyrk.com/mitosis.html
Results of Mitosis
• Division of nucleus
–Nuclei are identical to each other
•Same number & type of chromosomes
Asexual Reproduction
A type of reproduction - fission,
budding, and regeneration - in
which a new organism is produced
fro...
Asexual Reproduction
•Offspring produced from one
organism
•Hereditary information is
identical
•Mitosis is one form of as...
Sexual Reproduction
Meiosis
Sexual Reproduction
A type of reproduction in which
two sex cells, usually an egg and
a sperm, join to form a zygote,
whic...
Sexual reproduction
results in a great variety,
or diversity, of offspring.
Meiosis
• The nucleus divides twice
– Meiosis I
– Meiosis II
http://biotech-adventure.okstate.edu/low/basics/meiosis/diagram/
Interphase
• DNA is duplicated
Prophase I
• DNA shorten & thicken
– Forms chromatids / chromosomes
http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/prophase/leptotene/leptotene.gif
Metaphase I
•Copied chromatids /
chromosomes line up in
middle of cell
•Centromeres attach to
spindle fibers
http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/metaphase-I/metaphase-I.gif
Anaphase I
•Chromatid pairs are pulled
apart
–They DO NOT separate
•Move to ends of cell
http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/anaphase-I/anaphase-i.gif
Telophase I
•Cell divides
•No further replication of
hereditary material
http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/telophase-I/telophase-I.gif
There are now two
cells. Both cells have
full sets of genetic
material
(chromosomes)
Prophase II
•Similar to mitosis
–Starts with TWO cells instead
of one
•Spindle fibers appear
http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/prophase-II/prophase-II.gif
Metaphase II
•Duplicated chromatid /
chromosomes line up in
middle of cell
•Spindle fibers attach to
centromeres
http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/metaphase-II/metaphase-II.gif
Anaphase II
•Centromere divides
–Chromatids separate & move
to ends of cell
•Chromatids are now individual
chromosomes
http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/anaphase-II/anaphase-II.gif
Telophase II
•Spindle fibers disappear
•Nuclear membranes form at
each end of cell
•Cells divide
–Results in 4 cells
•Each...
http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/telophase-II/telophase-II.gif
Meiosis Animation
http://www.johnkyrk.com/meiosis.html
In summary:
Meiosis
• Two cells form during meiosis I
• In meiosis II, both of these cells
form two cells
• The two divisi...
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Cell reproduction

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LEADING TO MITOSIS AND MEIOSIS

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Cell reproduction

  1. 1. Leading to Mitosis & Meiosis by Muhammad Iqbal Khan SS Biology Email ID:mikhan1313@yahoo.com
  2. 2. http://biotech-adventure.okstate.edu/low/basics/mitosis/mitosis-diagram/diagram.gif
  3. 3. Cell Cycle http://www.bmb.psu.edu/courses/biotc489/notes/cycle.jpg
  4. 4. Mitosis • One type of cell division Cell process in which the nucleus divides to form two nuclei identical to each other, and identical to the original nucleus, in a series of steps (prophase, metaphase, anaphase, and telophase)
  5. 5. Mitosis allows for growth and replaces worn out or damaged cells.
  6. 6. Interphase • Period of growth & development • Hereditary information (DNA) copied (replicated / duplicated) • Cells that do not divide (nerves) are always in interphase
  7. 7. http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/interphase/interphase.gif
  8. 8. Prophase •DNA begins to shorten & thicken –Now called chromatids / chromosomes •Centromeres form •Nuclear membrane breaks apart •Spindle fibers form
  9. 9. http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/prophase/prophase.gif
  10. 10. Metaphase •Chromatids / chromosomes line up •Centromere attaches to spindle fibers
  11. 11. http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/metaphase/metaphase.gif
  12. 12. Anaphase •Centromeres divide •Spindle fibers shorten •Chromatid pairs separate – move to ends of cell •Chromatids are now called –Each ½ of the pair is now called a chromosome
  13. 13. http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/anaphase/anaphase.gif
  14. 14. Telophase •Spindle fibers disappear •Chromosomes uncoil •Nuclear membrane forms •Cell divides (cytokinesis)
  15. 15. http://biotech-adventure.okstate.edu/low/basics/mitosis/phases/telophase/telophase.gif
  16. 16. Interphase Prophase Metaphase Anaphase Telophase Interphase http://biology.nebrwesleyan.edu/benham/mitosis/
  17. 17. Mitosis Animation http://www.johnkyrk.com/mitosis.html
  18. 18. Results of Mitosis • Division of nucleus –Nuclei are identical to each other •Same number & type of chromosomes
  19. 19. Asexual Reproduction A type of reproduction - fission, budding, and regeneration - in which a new organism is produced from one parent and has DNA identical to the parent organism.
  20. 20. Asexual Reproduction •Offspring produced from one organism •Hereditary information is identical •Mitosis is one form of asexual reproduction
  21. 21. Sexual Reproduction Meiosis
  22. 22. Sexual Reproduction A type of reproduction in which two sex cells, usually an egg and a sperm, join to form a zygote, which will develop into a new organism with a unique identity.
  23. 23. Sexual reproduction results in a great variety, or diversity, of offspring.
  24. 24. Meiosis • The nucleus divides twice – Meiosis I – Meiosis II
  25. 25. http://biotech-adventure.okstate.edu/low/basics/meiosis/diagram/
  26. 26. Interphase • DNA is duplicated
  27. 27. Prophase I • DNA shorten & thicken – Forms chromatids / chromosomes
  28. 28. http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/prophase/leptotene/leptotene.gif
  29. 29. Metaphase I •Copied chromatids / chromosomes line up in middle of cell •Centromeres attach to spindle fibers
  30. 30. http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/metaphase-I/metaphase-I.gif
  31. 31. Anaphase I •Chromatid pairs are pulled apart –They DO NOT separate •Move to ends of cell
  32. 32. http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/anaphase-I/anaphase-i.gif
  33. 33. Telophase I •Cell divides •No further replication of hereditary material
  34. 34. http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/telophase-I/telophase-I.gif
  35. 35. There are now two cells. Both cells have full sets of genetic material (chromosomes)
  36. 36. Prophase II •Similar to mitosis –Starts with TWO cells instead of one •Spindle fibers appear
  37. 37. http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/prophase-II/prophase-II.gif
  38. 38. Metaphase II •Duplicated chromatid / chromosomes line up in middle of cell •Spindle fibers attach to centromeres
  39. 39. http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/metaphase-II/metaphase-II.gif
  40. 40. Anaphase II •Centromere divides –Chromatids separate & move to ends of cell •Chromatids are now individual chromosomes
  41. 41. http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/anaphase-II/anaphase-II.gif
  42. 42. Telophase II •Spindle fibers disappear •Nuclear membranes form at each end of cell •Cells divide –Results in 4 cells •Each with ½ the original number of chromosomes
  43. 43. http://biotech-adventure.okstate.edu/low/basics/meiosis/phases/telophase-II/telophase-II.gif
  44. 44. Meiosis Animation http://www.johnkyrk.com/meiosis.html
  45. 45. In summary: Meiosis • Two cells form during meiosis I • In meiosis II, both of these cells form two cells • The two divisions of the nucleus result in four sex cells (gametes) • Each has one-half the number of chromosomes in its nucleus that was in the original nucleus

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