10-2 Cell division
2 phases of cell division
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Mitosis: division of
the cell nucleus,
including DNA
replication.
Cytokinesis:
division of the
cytoplasm and
organelles
cytokinesis
Pair share: how is cytokinesis different from
mitosis?
Chromosomes

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Genetic material (DNA) is
usually in thin strands.
Before cell division, it
thickens into chromosomes
Each chromosome makes
a copy of itself , and
attaches to a centromere.
Nucleolus disappears.
Nuclear envelope breaks
down.
WB: how many copies of DNA are present before cell division?
Cell
cycle



A series of events that cells go through as they grow and
divide.
The cell grows, prepares to divide, then divides into 2
daughter cells.
The cycle resumes with each daughter cell.
Events of
the cell
cycle


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
G1: cells grow
S: DNA replicates
G2: preparation for mitosis
M: mitosis and cytokinesis
P/S: how long is interphase
compared to mitotic phase?
Prophase

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First and longest
phase
Chromosomes
become visible
Centrioles separate
to opposite sides
of the nucleus,
forming a spindle
of microtubules
Metaphase


Lasts only a few
minutes
Chromosomes line up
across the center of
the cell, held by fibers
of the spindle.
WB: where are the chromosomes in this phase?
Anaphase


Sister chromatids
split apart
Each moves to a
different pole of
the spindle as the
spindle fibers
contract.
Telophase

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Frog cell telophase
4th and last phase of mitosis
Chromosomes uncoil
Nuclear envelope re-forms around each cluster of
chromosomes
Spindle breaks apart
Nucleolus is visible in each daughter nucleus
P/S: how is telophase like the reverse of prophase?
Cytokinesis: division of the
cytoplasm


Animal cell


Plant
cell
In animal cells, the cell
membrane pinches in.
In plants, a cell plate
forms midway between
the divided nuclei.
The cell plate becomes a
membrane,
Later, a cell wall forms in
the cell plate.
Summary
4
5
3
Name the
stages of
the cell
cycle:
6
2
7
1