Cell Division

Two Parts of Cell Division

• (1) Mitosis –

• (2) Cytokinesis

The Cell Cycle

• Cell Cycle – series of events that cells go through as they grow and divide

• During the cell cycle, cells:– Grow– Prepare for division– Divide to form two daughter cells

Cell Cycle Cont.

• The cell cycle consists of four phases:– M Phase

– S Phase

– G1 Phase

– G2 Phase

Events of the Cell Cycle• Interphase – period of the cell cycle between cell

divisions – preparation for Mitosis• Not considered mitosis!!• Includes G1, S, and G2 phases

• G1 Phase –

• S –

• G2 –

Mitosis (4 Phases)

• Prophase – Longest phase of mitosis– Chromosomes become visible and coil tightly– Spindle fibers form– Nuclear envelope breaks down– Nucleolus disappears– Centrioles migrate to opposite sides of nucleus

http://www.google.com/url?sa=i&rct=j&q=prophase&source=images&cd=&cad=rja&docid=UVjF9-2H-PyA1M&tbnid=KRqHmfrtTCcZSM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.cwinstead.com%2Fcellcyclenotes.html&ei=FesiUfOeAqOEyAHL6YDABA&bvm=bv.42553238,d.aWc&psig=AFQjCNGYfGcIcpc_DlI0fjnWIPiSP2Auwg&ust=1361329291960836

Metaphase

• 2nd Phase of mitosis• Lasts only a few minutes• Chromosomes line up in the middle of the cell• Microtubules (spindle fibers) connect

centromere of each chromosome to spindle

http://www.google.com/url?sa=i&rct=j&q=metaphase&source=images&cd=&cad=rja&docid=Vun1l6Us4ETnFM&tbnid=md1VCo5bjlfN2M:&ved=0CAUQjRw&url=http%3A%2F%2Fjoshattualatinhigh4a.edublogs.org%2F2012%2F01%2F03%2Fcell-cycle-sequencing%2F&ei=busiUbn4C7H7yAG684DIBA&bvm=bv.42553238,d.aWc&psig=AFQjCNGZchFBtr5-gVD5r2tAe_95Bx71rg&ust=1361329382928764

Anaphase

• 3rd phase of mitosis• Centromeres split – allowing sister chromatids

to separate and become individual chromosomes

• Chromosomes separate and approach the poles of the spindle (opposite ends of the cell)

http://www.google.com/url?sa=i&rct=j&q=anaphase&source=images&cd=&cad=rja&docid=S9Rran8AGBxGoM&tbnid=d_15XPTNpHpfFM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.tumblr.com%2Ftagged%2Fcell%2520cycle%3Flanguage%3Dit_IT&ei=H-wiUZ-_C-TWyQGIpoHABA&bvm=bv.42553238,d.aWc&psig=AFQjCNGl5W7OWSNADdqD8FsmWn72txjE-w&ust=1361329563563203

Telophase

• Final stage of mitosis• Chromosomes disperse into a tangle of dense

material• Nuclear envelope reforms around

chromosomes• Spindle fibers break apart and nucleolus

becomes visible

Cytokinesis

• Cytokinesis – division of the cytoplasm– Completes M phase– The cytoplasm is pinched into equal parts– Each new part contains its own nucleus and

organelles