What: Cell division
When: New cells are needed
Where: Somatic cells (body cells)
Who: Somatic cells (Normal cells like in your toes)
What: Cellular reproduction for growth, the cell cycle
Where: Happens in somatic cells, regular body cells like in
Why: For growth (baby to adult) and to replace damaged
cells (heal a cut)
How: Duplicate cell parts making an exact copy of
cell; one "mother" cell becomes two identical "daughter"
Remember: Toes as is mi-toes-is (mitosis)
• Interphase is
NOT a part of
• Interphase the
before the DNA
then DNA is
proteins start to
• The microtubles
start moving to
one of the two
opposite end of
Prometaphase • Sometimes
considered part of
• Nuclear membrane
• Centrioles reach the
poles of the cell
• Proteins attach to
• The chromosomes
Dark region = condensing
chromatin, animal cell
• During metaphase,
region forming a
• They attach to sister
chromatids of each
• All chromosomes
line up at spindle
• Now in their most
between the two
• Now separate
Onion root tip
• Lastly, in
• New patches of
to form new
Cytokinesis & Daughter Cells
•Pinching of cytoplasm into
•Cell plate forms between
the two “new” cells.
•Cells now in interphase
Called daughter cells.
•Cells diploid, two each
type of chromosome – same
as parent cell's nucleus.
Thecell isengagedinmetabolicactivityandpreparingformitosis(thenextfourphasesthatleaduptoandinclude nucleardivision).
Chromosomesarenotclearlydiscernedinthenucleus,althougha darkspotcalledthenucleolusmaybevisible.Thecellmaycontaina pairofcentrioles(or
microtubule organizingcentersinplants)bothofwhichareorganizational sitesformicrotubules.Thisisthe longest stage.
Chromatin in the nucleus begins to condense and becomes
visible in the light microscope as chromosomes. The nucleolus
disappears. Centrioles begin moving to opposite ends of the cell and
fibers extend from the centromeres. Some fibers cross the cell to form the
Sometimes considered part of the prophase. When the nuclear membrane
disintegrates, the centrioles reach the poles of the cell, and the
chromosomes continue to contract. Proteins attach to the centromeres.
The chromosomes begin moving.
Spindle fibers align the chromosomes along the middle of the
cell nucleus. This line is referred to as the metaphase plate. This
organization helps to ensure that in the next phase, when the
chromosomes are separated, each new nucleus will receive one copy of
The paired chromosomes separate at the kinetochores and move to opposite
sides of the cell. Motion results from a combination of kinetochore
movement along the spindle microtubules and through the physical
interaction of polar microtubules.
Chromatids arrive at opposite poles of cell, and new membranes form
around the daughter nuclei. The chromosomes disperse and are no longer
visible under the light microscope. The spindle fibers disperse, and
cytokinesis or the partitioning of the cell may also begin during this stage.
In animal cells, cytokinesis results when a fiber ring composed of a protein
called actin around the center of the cell contracts pinching the cell into two
daughter cells, each with one nucleus. In plant cells, the rigid wall requires
that a cell plate be synthesized between the two daughter cells.
Can you identify the stages?
1. Are these
2. How can
Can you identify the stages?
6. Are these
7. How can
Purpose of Mitosis
• Increase the size of an organism.
• Replace worn out cells or repair
• Reproduce identical organisms, or
Comparing Mitosis & Meiosis
– Happens in somatic
cells, every day cells
in the body
– For growth
– Think: toestoes as is mi-as is mi-
– Happens in sex cells
– For sexual
– Think: e as in sex as
•Bio Review Cell Division
•Access Excellence at the National Health Museum About Biotech
•“The Cell Cycle & Mitosis Tutorial” The Biology Project University of
• Mitosis http://www.stanford.edu/group/Urchin/mitosis.htm
•eMuseum Minnesota State University
•Universlity of North Carolina at Charlotte