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Mitosis and Meiosis<br />Done by: RawanWalidshahien<br />
Mitosis<br />
Interphase<br />Interphase: <br />Nuclear envelope still there<br />And its before S phase because the centriolesarent dup...
Prophase<br />The chromatin condensed together to create visible chromosomes. <br />
Prophase<br />The spindle fibers also begin to form <br />Migration of the two pairs of the centrioles to the opposite sid...
Prophase<br />Gradual mixing of the  nucleolus with the rest of the nucleus.<br />The nuclear envelope  is almost complete...
Metaphase<br />Metaphase is marked by the alignment of all the chromosomes at the equatorial plane of the cell (the metaph...
Anaphase <br />Movements of the chromosomes occurs due to shortening of spindle microtubules and kinetochore movement alon...
Anaphase<br />Migration and arrival of the new chromosomes to the opposite poles of the cell. <br />
Telophase<br />During this stage, daughter chromosomes arrive at opposite poles of cell and the spindle fibers disappear. ...
Cytokinesis that takes place during telophase<br />Cytokinesis or cleavage of the cytoplasm of the cell begins.<br />
The result <br />myosin molecular motors attach to the actinand draw the membrane in -like a purse string.<br /> Once the ...
Meiosis<br />
Interphase<br />Interphase: “ before S phase”<br />the nuclear envelope still there<br />the chromosomes aren't condensed ...
Interphase<br />Interphase: “ after S phase”<br />the nuclear envelope still there<br />the chromosomes started to condens...
Prophase 1<br />Early prophase 1:<br />The chromatin condensed together to create visible chromosomes. <br />The spindle f...
Prophase 1<br />Prophase 1:<br />Same as the previous slide except that The two homologous chromosome now consists of four...
Prophase 1<br />Late prophase 1:<br />Crossing over takes place between the tetrad at the Chiasma *crossing over of segmen...
Metaphase 1<br />Metaphase1:<br />The homologous  paired chromosomes are shown to be connected by a terminal chiasma and a...
Anaphase 1<br />The terminal chiasma disappears and the chromosomes become free from each other.<br />The centromere remai...
Telophase<br />During this stage, cytokinesisoccurres by contraction of actin filaments around the center of the cell whic...
Interkinesis<br />The two daughter cells that resulted from the 1st meiotic division have 23 (1n) chromosomes and (2C) DNA...
Meiosis 2<br />no further replication occurs<br />chromosomes line up again (metaphase II)<br />sister chromatids separate...
The result<br />Four haploid cells * gamete cells* in which 2 are parental , and 2 are recombinant due to crossing over<br />
The end =D<br />Wish you the best of luck and inshallah we will all do good in the exams and pass and get HIGH grades =)<b...
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Mitosis and meiosis

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Mitosis and meiosis

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Transcript of "Mitosis and meiosis"

  1. 1. Mitosis and Meiosis<br />Done by: RawanWalidshahien<br />
  2. 2. Mitosis<br />
  3. 3. Interphase<br />Interphase: <br />Nuclear envelope still there<br />And its before S phase because the centriolesarent duplicated yet<br />
  4. 4. Prophase<br />The chromatin condensed together to create visible chromosomes. <br />
  5. 5. Prophase<br />The spindle fibers also begin to form <br />Migration of the two pairs of the centrioles to the opposite sides of the cell.<br />Thinning and gradual disappearance of nuclear envelope. <br />
  6. 6. Prophase<br />Gradual mixing of the nucleolus with the rest of the nucleus.<br />The nuclear envelope is almost completely disappeared<br />
  7. 7. Metaphase<br />Metaphase is marked by the alignment of all the chromosomes at the equatorial plane of the cell (the metaphase plate). <br />The nuclear membrane dissolves completely, marking the beginning of metaphase.<br />Attachment of the the spindle fibers to the centromere of the chromosome at a point called kinetochore.<br />
  8. 8. Anaphase <br />Movements of the chromosomes occurs due to shortening of spindle microtubules and kinetochore movement along the spindle fibers. <br />
  9. 9. Anaphase<br />Migration and arrival of the new chromosomes to the opposite poles of the cell. <br />
  10. 10. Telophase<br />During this stage, daughter chromosomes arrive at opposite poles of cell and the spindle fibers disappear. <br />The chromosomes change into chromatin and become invisible under the light microscope.<br />Nuclear envelope begins to form around the new nuclei. <br />
  11. 11. Cytokinesis that takes place during telophase<br />Cytokinesis or cleavage of the cytoplasm of the cell begins.<br />
  12. 12. The result <br />myosin molecular motors attach to the actinand draw the membrane in -like a purse string.<br /> Once the sister chromatids are separated, a ring of actin filaments (microfilaments) form a “contractile ring” around the middle of the cell<br />By the end of telophase, two independent daughter cells have been formed<br />
  13. 13. Meiosis<br />
  14. 14. Interphase<br />Interphase: “ before S phase”<br />the nuclear envelope still there<br />the chromosomes aren't condensed yet <br />Replication of centrioles didn’t occur<br />
  15. 15. Interphase<br />Interphase: “ after S phase”<br />the nuclear envelope still there<br />the chromosomes started to condense<br />Replication of centriolestook place<br />
  16. 16. Prophase 1<br />Early prophase 1:<br />The chromatin condensed together to create visible chromosomes. <br />The spindle fibers also begin to form at this time.<br />And centrioles begun to move away from each other<br />The maternal and paternal homologous chromosomes come close to each other and then align<br />Disappearance of the nuclear envelope is happening gradually<br />
  17. 17. Prophase 1<br />Prophase 1:<br />Same as the previous slide except that The two homologous chromosome now consists of four chromatids, so these chromosomes are called TETRAD.<br /> And now they are connected at the chiasma<br />
  18. 18. Prophase 1<br />Late prophase 1:<br />Crossing over takes place between the tetrad at the Chiasma *crossing over of segments of chromatids*<br />
  19. 19. Metaphase 1<br />Metaphase1:<br />The homologous paired chromosomes are shown to be connected by a terminal chiasma and arranged in the equatorial plate. <br />The mitotic spindle fibers connect the centromere of each chromosome on one side and the pole of the dividing cell on the other side <br />Attachment of the the spindle fibers to the centromere of the chromosome at a point called kinetochore.<br />Nuclear envelope is disappearing <br />
  20. 20. Anaphase 1<br />The terminal chiasma disappears and the chromosomes become free from each other.<br />The centromere remains undivided so sister chromatids move together to the opposite poles of the cell.<br />This movement occurs due to shortening of spindle microtubules and kinetochore movement along the spindle fibers. <br />Migration and arrival of the new chromosomes to the opposite poles of the cell. <br />Imp: here seperation of the chiasma takes place but NO division of centromere so the sister chromatids don’t separate here<br />
  21. 21. Telophase<br />During this stage, cytokinesisoccurres by contraction of actin filaments around the center of the cell which gives two daughter cells.<br />The chromosomes become thinner and then changed to chromatin.<br />The nuclear envelope reforms and the nucleolus reappears<br />
  22. 22. Interkinesis<br />The two daughter cells that resulted from the 1st meiotic division have 23 (1n) chromosomes and (2C) DNA. <br />These cells pass in a short interphase called interkinesis during which duplication of centrioles occurs but no replication to DNA takes place (NO S Phase). <br />Check in the next slide we have two yellow structure which is the centrioles so before we start meiosis 2 centrioles must be duplicated<br />
  23. 23. Meiosis 2<br />no further replication occurs<br />chromosomes line up again (metaphase II)<br />sister chromatids separate (telophase II and anaphase II)<br />the cells divide and chromosomes decondense (cytokinesis, telophase II)<br />
  24. 24. The result<br />Four haploid cells * gamete cells* in which 2 are parental , and 2 are recombinant due to crossing over<br />
  25. 25. The end =D<br />Wish you the best of luck and inshallah we will all do good in the exams and pass and get HIGH grades =)<br />You are the best future dentists <3<br />
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