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Mitosis  and the Cell Cycle
Why is mitotic cell division necessary? 1.  Asexual reproduction : ex: bacteria (binary fission) 2. To  replace damaged or dead cells 3.  Growth and embryonic development  of the organism dividing bone marrow cells    new blood cells Sand dollar embryo Amoeba reproducing
Binary Fission: how some bacteria reproduce
frog embryo
Phases of Mitosis
Interphase  (NOT PART OF MITOSIS) Chromatin has already duplicated (DNA replication complete) but is not visible to naked eye Early prophase : Spindle microtubules are growing Chromatin condenses and is packed into discrete chromosomes Late prophase : Each chromosome consists of two identical chromatids formed by DNA replication in interphase and held together by a centromere Spindle microtubules extend from each pole to the equator
Prometaphase: nuclear envelope disappears spindle microtubules attach to sister chromatids Metaphase: sister chromatids line up on the metaphase plate mitotic spindle forms
Anaphase: centromeres split, sister chromatids separate and each one is pulled to opposite ends of the cell cell begins to lengthen by the end of anaphase, there are 2 complete sets of genetic material at each pole
Telophase: nuclear envelope starts to reappear microtubule assembly starts to disintegrate chromatids begin to loosen Cytokinesis: The cell divides to form 2 cells with genetically identical nuclei
Animal Cell Division
Plant Cell Division
eukaryotic chromosomes (orange) in a kangaroo rat epithelial cell
Differences in Cell Division Between Plant and Animal Cells
Differences in Cell Division Between Plant and Animal Cells Plant Cells There are  no centrioles  in plant cells After anaphase, a  new cell wall  is formed across the equator of the cell,  with plasma membrane  on both sides.  This divides the cell into two cells Animal Cells Centrioles  are found at each pole of animal cells during mitosis After anaphase, the  plasma membrane  at the equator is pulled inwards until it meets in the center of the cell, dividing it into two cells
cell plate: dividing plant cell
onion root tip: lots of dividing cells