Download 10-2 - Kleins

Cell Division
10-2
Cell
Division
In Section 10-2 we will talk about cell
division of both prokaryotic and eukaryotic
cells
Even though prokaryotic cells do not have
a nucleus they can still go through cell
division
They simply make a copy of the genetic
material and split the total contents of the
cell in two
Eukaryotes have a much more complex
Chromosomes
In Eukaryotic cells,
the genetic
information that is
passed on is
contained in
chromosomes
Chromosomes are
made up of DNA
and proteins, as
you should recall
Chromosomes
Chromosomes are
not visible in most
cells except during
cell division
Well before cell
division,
chromosomes must
replicate
This makes pairs of
“sister chromatids”
Chromosomes
Each pair of “sister
chromatids” is
bound together
near the center by
a centromere
In a human cell
there are 46
chromosomes,
each of which
consist of a pair of
chromatids
The Cell Cycle
The life cycle of a
cell is known as the
cell cycle
This cycle
represents what
happens to a cell
during cell division
and between cell
divisions
The Cell Cycle
The “in between”
phases are
grouped together to
be called
interphase
Interphase consists
of three individual
phases
G1 Phase, S
Phase, G2 Phase
G1 Phase
The G1 phase is a
period of cell
growth
During this phase
the cell will get
slightly larger and
more mature
S Phase
The S Phase is the
period of DNA
replication
During this phase
DNA is replicated
so that when
division occurs,
there is a complete
set of DNA for each
daughter cell
G2 Phase
The G2 Phase is a
preparation for
Mitosis
During this phase
many of the
organelles needed
to assist in
replication are
produced
Mitosis
Mitosis
Biologists divide
the events of
mitosis into four
phases
Prophase
Metaphase
Anaphase
Telophase
Prophase
Prophase is the
first and longest
phase of mitosis
It takes up
approximately 4060% of the total
time of mitosis
Prophase
During prophase
chromatin
condenses into
chromosomes
Centrioles, two tiny
structures located
in the cytoplasm
near the nuclear
envelope, separate
and take up
positions on
Prophase
The spindle, a
fanlike microtubule
that helps separate
the chromosomes
later, forms during
prophase as well
The spindle will
become attached to
centromeres by
fibers
Prophase
The last thing to
occur in prophase
is the breaking
down of the nuclear
membrane
Metaphase
Metaphase is the
second phase of
mitosis
The chromosomes
line up across the
center of the cell
during metaphase
Anaphase
Anaphase is the
third phase of
mitosis
The sister
chromatids
separate into
individual
chromosomes and
are pulled apart
Telophase
Telophase is the
fourth and final
phase of mitosis
The chromosomes
will gather at
opposite ends of
the cell and start to
unwind back into
chromatin
The two new
nuclear envelops
Cytokinesis
There is one step
that must occur
after mitosis for
division to be
complete
Cytokinesis is the
splitting of the
cytoplasm into two
equal halves
This creates the