Mitosis
Mitosis – some basics
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form of nuclear division
 Therefore,
only occurs in eukaryotic cells
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(prokaryotes perform “binary fission”)
Mitosis
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Occurs in organisms for the purpose of:
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?
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?
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?
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?
Mitosis
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Goal:
Hardest Concept!!
Homolog
Homolog
Cooler View!
Interphase
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Not technically part of
mitosis
Cell spends >90% time
in this phase
DNA exists in
___________ form
Cell performs…..?
* Most important Fact …
Prophase
Events of Prophase
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*
*
*
*****
Prophase
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Is the cell to the left a
human cell?
How many chromosomes
are pictured?
Are the chromosomes
normal size or duplicated?
Which pieces of DNA are
identical to each other?
Metaphase

The duplicated chromosomes line up along the
“equator” of the cell.

What causes them to move?
Metaphase

How many
chromosomes are
pictured?
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Are the two red “X”s
identical to each other?
Anaphase
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Spindle fibers split the
duplicated chromosomes in
half.
The identical chromatids
are separated from each
other…. But now they are
normal sized chromosomes!
Will the two daughter cells
be genetically identical?
Telophase
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*
*
*
*
Telophase is called
“reverse prophase”
because…..
Telophase
In telophase, cytokinesis
occurs.
Cytokinesis -
Telophase
Q: Are the two daughter
cells genetically
identical to each
other????
Clones -
VI. Cytokinesis - division of the cytoplasm
A. In animal cells a contracting ring of
microfilaments tightens to form a cleavage
furrow
B. In plant cells a cell plate forms between daughter cells
Quick-Check: Identify the phase
IV. The Cell Cycle
Interphase
(90% of the cell cycle)
can be subdivided into:
1. G1 (Gap 1) is a time
of growth just after
division.
2. S (Synthesis) is when the chromosomes replicate.
3. G2 (Gap 2) is a period of additional growth and
preparation for division.
Thought Question:
When do you think a stimulus which results in
DNA replication would occur?
MITOSIS – BIG IDEAS

Occurs in all eukaryotic organisms

Each chromosome is copied. (Can you
describe how?)
One copy of every chromosome is distributed
to each of the two new daughter cells.

Thus  All body (somatic) cells contain full
set of chromosomes (therefore full set of
genes)
Questions
When do cells mitose?
What determines when cells start and stop
mitosing?
Can you think of a medical condition in which
you would like human cells to mitosis, (but
they normally don’t)?