Transcript Document

Mitosis & Cytokinesis
Objective
4a: I can recognize the stages
of mitosis from diagrams.
Objective 4b: I can put the stages of
mitosis in the proper order.
Objective #4c: I can state what types of
cells undergo mitosis, and why.
Objective #4d: I can list differences
between how animal and plant cells
divide.

Discuss the answers to the following questions
with the person next to you:
How is mitosis different from the phases of
interphase?
 What is the purpose of mitosis?
 What kinds of cells undergo mitosis?
 What are the phases of mitosis, and what happens in
each of them?


So; what do you know?
• G2 Interphase
cell—preparing
for mitosis. . .
How?

Prophase

Chromatin condenses into chromosomes
 Sets of sister chromatids
Nucleoli disappear
 Mitotic spindle begins to form as centrioles move to
opposite poles of the cell
 Nuclear envelope begins to fragment and break
down
 Microtubules of spindle (spindle fibers) attach to
centromeres of chromatids

at
ta
ch
...
t. .
.
ib
er
s
ef
Th
e
sp
i
nd
l
tic
ito
m
Th
e
ar
en
ve
sp
i
lo
pe
nd
l
es
st
a
ta
r
rts
..
...
se
de
n
co
n
Nu
cle
4.
es
3.
25% 25% 25% 25%
os
om
2.
Chromosomes
condense into
chromatin.
Nuclear envelope
starts to break
down.
The mitotic spindle
starts to form.
The spindle fibers
attach to the
centromeres.
Ch
ro
m
1.

Metaphase


Spindle fibers line sets of sister chromatids up on the
cell equator (middle of cell)
Preparation for anaphase, where chromatids get
pulled apart
...
m
ov
e
in
e
sl
es
at
id
Th
e
ce
nt
ri
ol
hr
om
Sis
te
rc
33%
th
e
u.
..
e.
.
33%
ls
st
il
re
es
a
3.
33%
os
om
2.
Chromosomes are
still sets of sister
chromatids attached
to spindle fibers at
their centromeres.
Sister chromatids
line up along the cell
equator.
The centrioles move
the sister chromatids
to the cell equator.
Ch
ro
m
1.

Anaphase

Sister chromatids are pulled apart at their
centromeres
 Each sister chromatid is now considered a
chromosome


Separated chromosomes are pulled to opposite
poles (ends) of the cell
By end of anaphase, each pole (ends) of cell has a
complete set of chromosomes
33%
ne
w
o
Tw
Sis
te
rc
hr
om
nu
c le
at
id
ia
re
sa
re
fo
r..
.
pu
. ..
e.
.
33%
ls
st
il
ar
e
es
3.
33%
os
om
2.
Chromosomes are
still sets of sister
chromatids at the
end of anaphase.
Sister chromatids
are pulled apart at
their centromeres
during anaphase.
Two new nuclei are
formed at the end of
anaphase.
Ch
ro
m
1.

Telophase

Two new daughter nuclei form at both poles
 Nuclear envelopes reform around each set of
chromosomes
 Chromosomes uncondense back into chromatin

Cytokinesis usually begins during telophase or
late anaphase
 Cleavage furrow appears (animal cells) or cell plate
appears (plants)
33%
at
m
nu
c le
if
or
co
nd
en
se
s
Tw
o
ne
w
at
in
Ch
ro
m
33%
...
to
.. .
..
a.
d
pu
lle
re
sa
3.
33%
at
id
2.
Chromatids are
pulled apart by their
centromeres
Chromatin
condenses to
chromosomes
Two new nuclei
form at each pole of
the cell
Ch
ro
m
1.
e
33%
M
et
ap
ha
s
se
ph
a
3.
33%
An
a
2.
Prophase
Anaphase
Metaphase
Pr
op
h
1.
as
e
33%
as
e
33%
Pr
op
h
rp
ha
se
33%
In
te
3.
ph
a
2.
Anaphase
Interphase
Prophase
An
a
1.
se
33%
50%
se
Fa
l
2.
True
False
Tr
ue
1.
50%

Differences in cytokinesis arise due to
presence/absence of cell walls

Animal cells: Can just pinch in two by a process
called cleavage
 Uses a ring of contractile proteins in its cell membrane
 Like the drawstring on sweatpants pulled tight enough
to cut you in half

Plant cells: Must build a new cell wall between the
two new nuclei
 Golgi sends out vesicles that builds the cell plate
..
las
ro
p
m
ch
lo
sis
ne
ls
us
e
cy
to
ki
Pl
a
nt
ce
l
ce
ll
nt
Pl
a
33%
t. .
33%
ak
tw
o.
..
in
ch
pi
n
ce
lls
al
3.
m
2.
Animal cells pinch in
two; plant cells build
a cell plate between
two new nuclei.
Plant cell cytokinesis
makes 4 new cells;
animal cell
cytokinesis only
makes 2 new cells.
Plant cells use
chloroplasts; animal
cells do not.
An
i
1.
33%
as
e
se
ph
a
25%
Pr
op
h
25%
An
a
Te
lo
ph
as
e
4.
ha
s
3.
et
ap
2.
Metaphase
Telophase
Anaphase
Prophase
M
1.
25%
e
25%
25%
25%
se
ph
a
An
a
M
et
ap
ha
s
e
e
4.
lo
ph
as
3.
25%
Te
2.
Prophase
Telophase
Metaphase
Anaphase
Pr
op
h
1.
as
e
25%
50%
se
50%
Fa
l
2.
True
False
Tr
ue
1.
ca
us
e
ce
lls
,
be
se
So
m
at
ic
ce
lls
,b
ec
au
rm
Sp
e
33%
t..
gu
..
33%
...
th
e
us
e
be
ca
lls
,
3.
33%
ce
2.
Body cells, because
they need to be small
and make more
identical cells.
Sperm cells, because
guys make a LOT of
them.
Somatic cells, because
the daughter cells
need to be genetically
different from the
parent cell.
Bo
dy
1.
ce
l
nt
Pl
a
al
m
An
i
ls
ce
lls
ha
ve
ca
n
to
pi
n
ch
bu
i
ld
in
.. .
.. .
33% 33%
id
i. .
es
di
v
ish
fin
sis
3.
33%
in
e
2.
Cytokinesis finishes
dividing the nucleus
of the daughter cells.
Animal cells can
pinch in two because
they don’t have a cell
wall.
Plant cells have to
build a new cell wall
between the two new
nuclei to finish
dividing completely.
Cy
to
k
1.