Download Spindle fibers

Mitosis &
Cytokinesis
Why do cells divide by
Mitosis?
• Growth &Repair
• Reproduction of
single celled
organisms under?
conditions
• constant
environment
Amobea
Reproducing
Cells dividing by Mitosis…….
Skin
• Identical to
original cell
• Same
chromosome #
• Identical
chromosome
makeup
Cell Cycle
“G” or Growth
1 phase
“S” or DNA
Synthesis
24 hours
Growth 2
/
/
/
“M” or
Mitosis
phase
Where is DNA located?
1. Nucleus
2. Chromosomes
DNA
Duplicated Chromosome
(Late Interphase):
Sister
Chromatids
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
• Chromoso
mes line
up midcell
• 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 Anaphase
Interphase
Cancerous cells……...
1.Divide too many
times
2.Divide into more
than two cells!
• Masses of cells =
• “tumors”
• benign
• malignant