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