Section 5-2Section 5-2“Mitosis“Mitosis””

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5.2 Mitosis and Cytokinesis

KEY CONCEPT KEY CONCEPT Cells divide during mitosis and Cells divide during mitosis and cytokinesis.cytokinesis.

5.2 Mitosis and Cytokinesis

DNA doublehelix

DNA andhistones

Chromatin SupercoiledDNA

•When the cell grows large enough it needs to When the cell grows large enough it needs to dividedivide

•Cell Division is called Cell Division is called MitosisMitosis

•First the DNA must coil up to make First the DNA must coil up to make ChromosomesChromosomes

5.2 Mitosis and Cytokinesis

DNA strands in the nucleus are called DNA strands in the nucleus are called chromatinchromatin

• One half of a duplicated One half of a duplicated chromosome is a chromosome is a chromatidchromatid

• Sister chromatids are Sister chromatids are held together at the held together at the centromerecentromere

• Telomeres protect DNA Telomeres protect DNA and do not include and do not include genesgenes Condensed, duplicated Condensed, duplicated

chromosomechromosome

chromatidchromatid

telomeretelomere

centromerecentromere

telomere

5.2 Mitosis and Cytokinesis

Parent cell

centriolescentrioles

spindle fibersspindle fibers

centrosomecentrosome

nucleus withnucleus withDNADNA

• Interphase Interphase prepares the cell to prepares the cell to dividedivide

• During During interphase, the interphase, the DNA is DNA is duplicatedduplicated

Mitosis produces 2 genetically Mitosis produces 2 genetically identicalidentical daughter cells daughter cells

5.2 Mitosis and Cytokinesis

• Mitosis divides the cell’s nucleus in 4 phasesMitosis divides the cell’s nucleus in 4 phases

ProphaseProphase: chromosomes : chromosomes condense and spindle fibers condense and spindle fibers formform

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5.2 Mitosis and Cytokinesis

MetaphaseMetaphase: chromosomes : chromosomes line up in the line up in the middlemiddle of the of the cellcell

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5.2 Mitosis and Cytokinesis

AnaphaseAnaphase: sister chromatids : sister chromatids separate to opposite sides of separate to opposite sides of the cellthe cell

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5.2 Mitosis and Cytokinesis

TelophaseTelophase: the new nuclei form : the new nuclei form and chromosomes begin to and chromosomes begin to uncoiluncoil

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5.2 Mitosis and Cytokinesis

• CytokinesisCytokinesis (division of the cytoplams) (division of the cytoplams) differs in animal and plant cellsdiffers in animal and plant cells

–CytokinesisCytokinesis splits the 2 new splits the 2 new cells…cells…

– In animal cells, In animal cells, the membrane the membrane pinches closedpinches closed

– In plant cells, a In plant cells, a cell platecell plate forms forms