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Mitosis

Mitosis. The division of the nucleus. © 2010 Paul Billiet ODWS. Conception. All animals begin as a fertilised egg cell (a zygote). Image Credit: Zygote. Then it divides…. Image Credit: www.ehd.org/. … and divides. Released into the Public Domain by Jrockley.

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Mitosis

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  1. Mitosis The division of the nucleus © 2010 Paul Billiet ODWS

  2. Conception • All animals begin as a fertilised egg cell (a zygote) Image Credit: Zygote

  3. Then it divides… Image Credit: www.ehd.org/

  4. … and divides Released into the Public Domain by Jrockley

  5. Image Credit: www.scienceclarified.com Until it becomes an embryo

  6. But what actually happens when a cell divides? • http://video.google.com/videoplay?docid=-5522357274832025243&q=mitosis&total=368&start=0&num=10&so=0&type=search&plindex=2 • http://www.johnkyrk.com/mitosis.html • http://www.bio.unc.edu/faculty/salmon/lab/mitosis/mitosismovies.html

  7. Image Credit: www.bioweb.uncc.edu/

  8. Interphase: In between cell divisions Centriole The working cell • It grows in size (protein synthesis) • It copies it’s genetic material (replication) Cytoplasm Nucleus Plasma membrane Nucleus envelope Nucleolus © 2010 Paul Billiet ODWS

  9. Image Credit: www.bioweb.uncc.edu/

  10. Prophase: Division begins Centriole divides Treads appear in the nucleus = Chromosomes condensing Nucleus swells Nucleolus disappears © 2010 Paul Billiet ODWS

  11. Nucleus envelope breaks down Chromosomes appear as two threads (the chromatids) joined by a constriction (the centromere) End of prophase: The nucleus disappears Spindle fibres grow out from the ends of the cell Sister chromatids Centromere © 2010 Paul Billiet ODWS

  12. Image Credit: www.bioweb.uncc.edu/

  13. Metaphase: The chromosomes are organised • Chromosomes line up across the equator of the spindle • Joined to fibres by their centromeres © 2010 Paul Billiet ODWS

  14. Image Credit: www.bioweb.uncc.edu/

  15. Anaphase: The chromosomes split • The sister chromatids of each chromosome split • The spindle pulls one to each pole © 2010 Paul Billiet ODWS

  16. Image Credit: www.bioweb.uncc.edu/

  17. Telophase: The end of mitosis • The nuclei reform • Each one contains a complete set of chromosomes • A new nuclear envelop forms • The chromosomes uncoil • The cytoplasm divides in two to form two identical daughter cells • The cells goes back to work © 2010 Paul Billiet ODWS

  18. Multicellular organisms copy their chromosomes before cell division They must grow to a mature size The nucleus divides, distributing the chromosomes into two equal groups Chromosomes and cell division Interphase Mitosis • The cytoplasm then divides each part taking a nucleus Cytokinesis © 2010 Paul Billiet ODWS

  19. The cell cycle Some cells may stay in this stage for over a year Cytokinesis division of the cytoplasm G1 + S + G2 = INTERPHASE G0 M First growth phase. Varies in length Mitosis G1 G2 INTERPHASE Second growth period Copying of chromosomes S © 2010 Paul Billiet ODWS

  20. Cell cycles are not uniform © 2010 Paul Billiet ODWS

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