Mitosis & Cell Division Mitosis & Cell Division
Centrioles
Nuclear envelope
Chromatin
Interphase
-Cell Grows -Genetic Material Replicates -Errors are corrected
INTERPHASE
MitosisMitosis A continuous process that is divided A continuous process that is divided
into four stages:into four stages:– Prophase, Prophase, – Metaphase, Metaphase, – Anaphase, Anaphase, – TelophaseTelophase
The end of Mitosis is marked by the The end of Mitosis is marked by the separation of the sister chromatids, separation of the sister chromatids, forming two nuclei that include a forming two nuclei that include a copy of each chromosomecopy of each chromosome
ProphaseProphase Nuclear envelope begins to break Nuclear envelope begins to break
downdown Chromosomes condense and become Chromosomes condense and become
visiblevisible Microtubules form around nucleusMicrotubules form around nucleus Centrioles segregate to opposite Centrioles segregate to opposite
ends of the cellends of the cell Towards the end of this phase, the Towards the end of this phase, the
microtubules attach to the microtubules attach to the centromere of the chromatids.centromere of the chromatids.
Prophase
Prophase in Onion Root Tip
MetaphaseMetaphase Sister chromatids begin to line up Sister chromatids begin to line up
towards the middle of the cell towards the middle of the cell forming the forming the metephase platemetephase plate
The metephase plate lines up perpendicular The metephase plate lines up perpendicular to the spindles such that each new nuclei to the spindles such that each new nuclei ends up with one copy of each chromosomeends up with one copy of each chromosome
Metaphase
Metaphase in Onion Root Tip
AnaphaseAnaphase Beginning of Beginning of chromosome segregationchromosome segregation
– Proteins break down centromeresProteins break down centromeres– Motor proteins begin to move chromosomes Motor proteins begin to move chromosomes
to opposite ends of the cellto opposite ends of the cell If there are errors during this stage, the If there are errors during this stage, the
chromosomes do not separate equally, chromosomes do not separate equally, causing causing aneuploidaneuploid cells. cells.– One nucleus has a greater number of One nucleus has a greater number of
chromosomes than the other.chromosomes than the other.Q: Why do you think this may be harmful to Q: Why do you think this may be harmful to
the organism?the organism?
Anaphase
Anaphase in Onion Root Tip
TelophaseTelophase Chromosomes begin to expand and Chromosomes begin to expand and
are no longer visibleare no longer visible The nuclear envelope begins to The nuclear envelope begins to
reform, creating two nucleireform, creating two nuclei
Telophase
Telophase in Onion Root Tip
CytokinesisCytokinesis The plasma membrane begins to squeeze The plasma membrane begins to squeeze
between the two newly formed nucleibetween the two newly formed nuclei The cell is divided into twoThe cell is divided into two If the cell has a cell wall, vesicles with If the cell has a cell wall, vesicles with
cellulose surround the nucleicellulose surround the nuclei– The vesicles fuse to create the new plasma The vesicles fuse to create the new plasma
membranemembrane– The cellulose inside the vesicles then extend the The cellulose inside the vesicles then extend the
cell wall.cell wall. The new cells now enter GThe new cells now enter G11
Cytokinesis in Animal Cell
Cytokinesis in Plant Cell
ReferencesReferences http://www.biology.arizona.edu/cell_bio/tutorials/chttp://www.biology.arizona.edu/cell_bio/tutorials/c
ell_cycle/cells3.htmlell_cycle/cells3.html http://www.botany.org/plantimages/Mitosis.phphttp://www.botany.org/plantimages/Mitosis.php BSCS Biology: A Molecular ApproachBSCS Biology: A Molecular Approach (8 (8thth ed.). ed.).
(2001). (2001). Columbus, OH: Glencoe/McGraw-HillColumbus, OH: Glencoe/McGraw-Hill Cooper, G. M. (2000). Cooper, G. M. (2000). The Cell: A Molecular The Cell: A Molecular
ApproachApproach (2(2ndnd ed). Washington, DC: ASM Press ed). Washington, DC: ASM Press http://faculty.clintoncc.suny.edu/faculty/Michael.Ghttp://faculty.clintoncc.suny.edu/faculty/Michael.G
regory/files/Bio%20101/Bio%20101%20Lectures/regory/files/Bio%20101/Bio%20101%20Lectures/Mitosis/mitosis.htmMitosis/mitosis.htm