MitosisMitosisCh 8. 2 Cell DivisionCh 8. 2 Cell Division

Cell CycleCell Cycle

Interphase: Interphase: –G1: Cell growsG1: Cell grows–S: DNA replicatesS: DNA replicates–G2: Organelles G2: Organelles replicatereplicate

MitosisMitosis

The process of dividing The process of dividing nuclear materialnuclear material

VocabVocabWRITE THESE DEFINITIONS ON TOP OF YOUR WRITE THESE DEFINITIONS ON TOP OF YOUR NOTES!NOTES! Microtubules: protein structures Microtubules: protein structures

that are part of a cell’s that are part of a cell’s cytoskeletoncytoskeleton– Spindle: a bundle of microtubules Spindle: a bundle of microtubules

that separate chromosomes during that separate chromosomes during mitosismitosis

– Centriole: microtubule structure that Centriole: microtubule structure that helps organize the spindle fibers helps organize the spindle fibers during cell divisionduring cell division

– Aster: microtubules surrounding the Aster: microtubules surrounding the centriolecentriole

ProphaseProphasea.a. ChromosomesChromosomes become become

visible.visible.b.b. CentriolesCentrioles move to move to

opposite poles of the cell.opposite poles of the cell.c.c. Microtubules extend from Microtubules extend from

the centrioles to form the centrioles to form astersasters

ProphaseProphase

d.d. Microtubules form spindle Microtubules form spindle fibers.fibers.

e.e. Spindle fibers become Spindle fibers become attached to centromeres.attached to centromeres.

f.f. Nuclear membraneNuclear membrane disappears.disappears.

MetaphaseMetaphase

a.a. Centromeres of the Centromeres of the chromosomes line up chromosomes line up on the equatoron the equator..

AnaphaseAnaphase

a.a. Centromeres divideCentromeres divide..b.b. ChromatidsChromatids move to move to

opposite poles.opposite poles.

TelophaseTelophase

a.a. Chromosomes reach the Chromosomes reach the poles of the cell.poles of the cell.

b.b. Chromosomes Chromosomes uncoiluncoil..c.c. Spindle and asters Spindle and asters

disappeardisappear..d.d. Nuclear membrane forms.Nuclear membrane forms.

Cytokinesis (in Cytokinesis (in animals)animals)a.a. Begins during late Begins during late

anaphase.anaphase.b.b. Cytoplasm is pinched off Cytoplasm is pinched off

by cell membrane.by cell membrane.c.c. Results in two new cells.Results in two new cells.

Mitosis in plantsMitosis in plants

Main events are the sameMain events are the samePlants don’t have Plants don’t have

centrioles or asters.centrioles or asters. In cytokinesis, a In cytokinesis, a cell plate cell plate

forms between the new forms between the new cells.cells.

The Rate of MitosisThe Rate of MitosisWRITE THESE DOWN!WRITE THESE DOWN! Cells undergo mitosis at different Cells undergo mitosis at different

rates.rates. Mitosis speeds up during an Mitosis speeds up during an

injury.injury. Mitosis slows down with aging.Mitosis slows down with aging. Cells that undergo very fast Cells that undergo very fast

uncontrolled mitosis form cancer.uncontrolled mitosis form cancer.

Name the stage of each Name the stage of each cell.cell.

A

B

DC