The Cell Cycle &

Cell Division

Cell  Division—Mitosis  Notes Cell  Division  —  process  by  which  a  cell  divides  into  2  new  cells   • Why  do  cells  need  to  divide?   1. Living  things  grow  by  producing  more  cells,  NOT  because  each  cell  increases  in  size

2.  Repair  of  damaged  Cssue 3. If  cell  gets  too  big,  it  cannot  get  enough  nutrients  into  the  cell  and  wastes  out  of  the  cell

The Cell Cycle

http://www.nobel.se/medicine/laureates/2001/press.html

Cell cycle can be divided into stages

•  Interphase: G1, S, G2

•  Mitosis: Prophase, Metaphase, Anaphase, Telophase & Cytokinesis

Interphase The cell prepares for division and carries out normal cell functions

•  G1- primary growth phase

•  S- DNA replicates •  G2- Cell continues to

grow in size and organelles replicate

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Interphase – S Stage

Two identical copies of DNA

Original DNA

Interphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

MITOSIS

Mitosis

The process of cell division which results in the production of two daughter cells

from a single parent cell.

The daughter cells are identical to one another and to the original parent

cell.

Prophase The cell prepares for nuclear division

–  Packages chromatin (DNA) into visible chromosomes

- Spindle fibers form and nuclear membrane breaks down

Prophase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Metaphase The cell prepares chromosomes for

division –  Chromosomes line up

at the center of the cell –  Spindle fibers attach to

chromosomes at the centromere

Metaphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Anaphase The chromosomes divide

–  Spindle fibers pull sister chromatids apart to opposite poles of the cell.

Anaphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Telophase and Cytokinesis The cytoplasm divides

–  DNA spreads out –  2 nuclei form

around each set of sister chromatids

–  Cytokinesis: Cell membrane pinches in to form the 2 new daughter cells

Telophase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

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Daughter Cells of Mitosis ü Have the same number of

chromosomes as each other and as the parent cell from which they were formed

ü Identical to each other, but smaller than parent cell

ü Must grow in size to become mature cells (G1 of Interphase)