Transcript Bridget Manley Mitosis Power Point

Prophase
Metaphase
1.
2.
Anaphase
3.
START
Telophase
4.
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In prophase, the
chromatin condenses
into discrete
chromosomes. The
nuclear envelope
breaks down and
spindles form at
opposite "poles" of
the cell. Many
consider prophase to
be the first true step
of the mitotic process.
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Chromatin fibers become coiled into chromosomes with each
chromosome having two chromatids joined at a centromere.
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The mitotic spindle, composed of microtubules and proteins,
forms in the cytoplasm.
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In animal cells, the mitotic spindle initially appears as
structures called asters which surround each centriole pair.
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The two pair of centrioles (formed from the replication of one
pair in Interphase) move away from one another toward
opposite ends of the cell due to the lengthening of the
microtubules that form between them.
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The nuclear envelope breaks up.
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Polar fibers, which are microtubules that make up the spindle
fibers, reach from each cell pole to the cell's equator.
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Kinetochores attach to a type of microtubule called
kinetochore fibers.
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The kinetochore fibers "interact" with the spindle polar fibers
connecting the kinetochores to the polar fibers.
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The chromosomes begin to migrate toward the cell center.
Plant Cells
Animal Cells
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In metaphase,
the spindle fully
develops and the
chromosomes
align at the
metaphase plate (a
plane that is
equally distant
from the two
spindle poles).
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The nuclear membrane disappears completely.
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In animal cells, the two pair of centrioles align at opposite poles of
the cell.
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Polar fibers (microtubules that make up the spindle fibers) continue
to extend from the poles to the center of the cell.
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Chromosomes move randomly until they attach (at
their kinetochores) to polar fibers from both sides of
their centromeres.
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Chromosomes align at the metaphase plate at right angles to the
spindle poles.
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Chromosomes are held at the metaphase plate by the equal forces of
the polar fibers pushing on the centromeres of the chromosomes.
Plant Cells
Animal Cells
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In anaphase, the paired
chromosomes (sister
chromatids) separate and
begin moving to opposite
ends (poles) of the cell.
Spindle fibers not
connected to chromatids
lengthen and elongate the
cell. At the end of
anaphase, each pole
contains a complete
compilation of
chromosomes.
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The paired centromeres in each distinct chromosome begin to move
apart.
Once the paired sister chromatids separate from one another, each
is considered a "full" chromosome. They are referred to as daughter
chromosomes.
Through the spindle apparatus, the daughter chromosomes move to
the poles at opposite ends of the cell.
The daughter chromosomes migrate centromere first and
the kinetochore fibers become shorter as the chromosomes near a
pole.
In preparation for telophase, the two cell poles also move further
apart during the course of anaphase. At the end of anaphase, each
pole contains a complete compilation of chromosomes.
Plant Cells
Animal Cells
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In telophase, the
chromosomes are
cordoned off into
distinct new nuclei
in the emerging
daughter cells.
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The polar fibers continue to lengthen.
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Nuclei (plural form of nucleus) begin to form at opposite
poles.
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The nuclear envelopes of these nuclei are formed from
remnant pieces of the parent cell's nuclear envelope and from
pieces of the endomembrane system.
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Nucleoli (plural form of nucleolus) also reappear.
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Chromatin fibers of chromosomes uncoil.
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After these changes, telophase/mitosis is largely complete
and the genetic "contents" of one cell have been divided
equally into two.
Plant Cell
Animal Cell
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Spindle Fibers-an aggregate of microtubules
that move chromosomes during cell division.
Asters-radial microtubule arrays in animal
cells which are located around each pair of
centrioles.
Kinetochores-specialized regions in the
centromeres of chromosomes
Daughter Cells-chromosome resulting from
the separation of sister chromatids.
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The End!