Transcript 79099_Mitosis

Stages of Mitosis
What’s happening and where are
things moving to?
Interphase
 Represents the longest time period
of the cell cycle
 Busiest phase of the cell cycle
 G1: Cell grows in size and
protein production is high
 S: Cell copies it’s chromosomes
 G2: After DNA is replicated
organelles such as
mitochondria are manufactured
and cell parts needed for cell
division are assembled.
Prophase - Formation of sister chromatids
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Chromatin coils up and chromosomes
become visible.
Formation of sister chromatids held
together by the centromere.
Nucleus begins to disappear
Nucleolus disintegrates.
Centrioles begin to move to opposite
ends of the cell. ( animal cells)
Spindle begins to form - made from thin
fibers of microtubules.
In plant cells, spindle forms without
centrioles.
Metaphase - aligning into the middle
 Shortest phase of mitosis
 Double chromosomes ( sister
chromatids ) become attached to
spindle fibers by their
centromeres.
 Chromosomes pulled by spindle
fibers to the middle of the cell.
 Each sister chromatid is attached
by it’s spindle fiber that extends
to the oppoosite pole.
Anaphase - Separation of sister chromatids
 Centromeres split
apart.
 Chromatid pairs
separate from each
other.
 Pulled apart by the
shortening of the
microtubules in the
spindle fibers.
Telophase
 Begins when chromatids
reach the opposite poles.
 Spindle breaks down
 Nucleolus reappears
 New nuclear envelope forms
around each set of
chromosomes.
 Lastly, a new double
membrane forms between
two new nuclei. This is called
cytokinesis.
Cytokinesis – cell division
 Final stage of cell reproduction
 Division of the cytoplasm into
approximately equal halves, resulting
in a roughly equal distribution of
organelles in each of the daughter
cells.
 In cells lacking a cell wall occurs
through a pinching inward
 Organisms with a cell wall undergo a
process through which a so-called
cell plate is built from the middle of
the cell outward to the membrane.