Mitosis & Cytokinesis

Cell Growth and Reproduction Ch. 8.2

Why do cells divide by Mitosis?

• Growth &Repair• Reproduction of

single celled organisms under? conditions

• constant environment

AmobeaReproducing

Cells dividing by Mitosis…….

• Identical to original cell

• Same chromosome #

• Identical chromosome makeup

Skin

Cell Cycle

24 hours

“G” or Growth 1 phase

“S” or DNASynthesis

Growth 2

“M” orMitosisphase

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Where is DNA located?1. Nucleus

2. ChromosomesDNA

Duplicated Chromosome(Late Interphase):

SisterChromatids

Centromere

Spindle & spindle fibers: Pull apart the sister chromatids

Spindle fibers

Cytokinesis:cell’s cytoplasm divides & splits apart

Stages of Mitotic Cell Division

• Prophase

• Metaphase

• Anaphase

• Telophase

• “1st”• “middle”• “apart”• “far” or

separate

Interphase

• “Intermission”

• Normal metabolic activities

• Major state

• DNA=

chromatin

Late Interphase• Prepares for

mitosis• DNA doubles=• Sister chromatids• Centrioles double

in• animals

Prophase • Nuclear membrane disappears

• Doubled DNA = condensed

• “chromosomes”• Spindle fibers

Metaphase

• Chromosomes line up mid- cell

• Facing inward

Anaphase• Chromosomes move

to opposite poles at• Centrioles in• animals• Spindle apparatus

in• plants

Telophase

• Cells divide• Cell plate or

membranes form

• Nucleus reappears

Returns to Interphase• “Intermission”• Normal metabolic

activities• Major state • DNA=chromatin

Plant versus Animal Mitosis

Plant:

• Cell wall from

• cell plate in telophase

• Sindles

Animal:

• No cell wall

• membrane cytokinesis

• Centrioles

Animal Telophase

Interphase

Plant AnaphaseInterphase

Cancerous cells……...

1.Divide too many times

2.Divide into more than two cells!

• Masses of cells =

• “tumors”

• benign

• malignant