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5.2 Mitosis and Cytokinesis
Purpose of Cell Division in Multicellular Organisms
• Growth – get bigger by making more cells
• Replacement – replace cells that die
• Repair – replace cells that get damaged
• Maintain size limit (surface area to volume ratio)
• Asexual Reproduction
Purpose of Cell Division in Unicellular Organisms
• Asexual reproduction Make new organism
Cell Division – in Eukaryotes
Pancreatic cells
 2 Types of cell division:
 1. Mitosis: division of somatic cells
 2. Meiosis: creation of new sex cells
Sperm cells
Human egg cell
Cell Division - Prokaryotes
 Binary Fission – asexual reproduction
method to make a new organism
Warm Up to ……Cell Division
• Name the 3 types of cell reproduction
and their final product (number and type
of cell made)
• Which two types make clones genetically
same
• Which makes genetically different cells
• Haploid vs Diploid
• Which chrom number means 2 of each
chrom type ? Which means only 1 of
each chrom type? Which do sex cells
have?
5.2 Mitosis and Cytokinesis
It’s the CELL CYCLE !!
Cell Cycle
 Most cells have a life
cycle that includes:
,
 Growth
 Doing its job
 Dividing
INTERPHASE
2 Major Stages of the Cell cycle
 Interphase –
 Cell carries out its special job, Prepares
for Cell division by doublin’ all of its
organelles and chromosomes
 Cell Division (M phase)
 Evenly divides the chromosomes and
other cell contents into two separate cells
Cell Cycle - Interphase
 The longest
phase in the cell
cycle is
interphase.
 Interphase has 3
stages:
G1, S, and G2.
G1 – Gap 1
 Longest period of

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
cell’s life
Cell carries out it job
Grows in size
Must pass 1st critical
checkpoint before
entering “S” phase
Cells that aren’t
destined to divide
enters G0 stage.
Ex. Nerve cells
S -“Synthesis”
 DNA replicates –creates a doubled chromosome each strand is
sister chromatid
 The DNA in each strand is genetically identical
chromatid
condensed
chromosome
centromere
G2 - Gap 2
 2nd checkpoint –
ensure DNA and
organelles replicate
properly to prepare
for division
Why is Interphase Important
 Interphase is NOT part of cell division
 BUT
 Interphase processes are important in
preparing the cell to divide properly
Cell Division (M or Mitosis)
2 Stages of Cell Division
 Mitosis – Division of the chromosomes
 into 2 new nuclei
4 Stages:
 Prophase
 Metaphase
 Anaphase
 Telophase
 Cytokinesis – Division of the cytoplasm
into 2 new cells.
Length of Time Cell spends in the Cell Cycle
 Varies by cell type.
 Skin cells and intestinal lining cells
frequently divide
 Other cells like brain and nerve rarely, if
ever divide – they enter the G0 stage.
5.2 Mitosis and Cytokinesis
KEY CONCEPT
Cells division occurs through mitosis and cytokinesis.
Interphase
• Longest phase of cell cycle
• Cell grows and does its job
(metabolically active)
• Chromatin in nucleus
• Nucleus and Nucleus visible
• Duplicates organelles in “G1”
phase and chromosomes
in “S” phase
Parent cell
centrioles
spindle fibers
centrosome
nucleus with
DNA
5.2 Mitosis and Cytokinesis
chromatid
• Chromosomes doubled in S phase
• Each half is called a chromatid.
centromere
• Sister chromatids are held together
at the centromere.
Condensed, duplicated chromosome
5.2 Mitosis and Cytokinesis
Draw Interphase
5.2 Mitosis and Cytokinesis
Draw Interphase
5.2 Mitosis and Cytokinesis
INTERPHASE ends
4 Stages of Mitosis:
• Prophase
• Metaphase
• Anaphase
• Telophase
MITOSIS begins:
PROPHASE
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Longest stage of Mitosis
Chromosomes condense (coil up) and become visible
Nuclear membrane and nucleolus break down
Centrioles move to opposite poles of the cell
Asters and spindles fibers form between poles
Chromosomes condense and can be seen
Chromatin
Chromosomes
5.2 Mitosis and Cytokinesis
Early Prophase
Late Prophase
 Nuclear membrane disappears.
Draw Prophase
Prophase
2
3
1
4
5
Prophase
2
3
Centriole
4
5
Prophase
Spindle fibers
3
Centriole
4
5
Prophase
Spindle fibers
Aster
Centriole
4
5
Prophase
Spindle fibers
Aster
Centriole
5
Sister
chromatids
Prophase
Spindle fibers
Aster
Centriole
Centromere
Sister
chromatids
5.2 Mitosis and Cytokinesis
METAPHASE
• Shortest phase of mitosis
• Chromosomes line up at the cell’s equator
• Spindle fibers attach to centromeres on the
chromosomes.
Centriole
Spindle
fibers
5.2 Mitosis and Cytokinesis
METAPHASE
Draw Metaphase
ANAPHASE
• Centromeres divide and the sister chromatids split apart
and move to opposite poles.
• Individual chromatids now called Chromosomes
5.2 Mitosis and Cytokinesis
Anaphase
Draw Anaphase
Telophase
 Chromosomes uncoil.
 The nuclear membrane
re-forms around the two
sets of chromosomes.
 Two new nuclei formed
 END OF MITOSIS
Draw Telophase
Cytokinesis
 Cytoplasm divides
 Two separate daughter cells
are formed
 Occurs differently in animal
and plant cells
Cytokinesis in Animal Cells
 Animal cells have a
flexible cell
membrane
 Cytoplasm pinches
in creating a
Cleavage Furrow
 Two separate
Daughter Cells are
formed
Cleavage furrow in a dividing frog cell.
Cytokinesis in Plant Cells
 In plant cells, a Cell Plate forms
and creates a cell wall that
seperates the cytoplasm into 2
separate daughter cells
Cell Plate forming
ANIMAL vs. PLANT MITOSIS
 ANIMAL CELL
 Centriole and
aster present
 Daughter cells
separated by
cleavage furrow
 PLANT CELL
 No visible
centriole or aster
 Daughter cells
separated by cell
plate
5.2 Mitosis and Cytokinesis
Cytokinesis – Cytoplasm Division
Animal Cell
Cleavage Furrow
Plant Cell
Cell Plate
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
Identify each of the following cell cycle stages
5.2 Mitosis and Cytokinesis
Let’s Review the Events of the Cell Cycle
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Cell Cycle and Mitosis 3D Video
Cell Cycle Video
Cell Cycle Video #2
Cell Cycle Video #3
Cell Cycle tutorial #1
Cell Cycle tutorial #2
Animal Cell Division
Plant Cell Division#1
Plant Cell Division #2
Meiosis in 3D
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
1. In which stage of the cell cycle do cells grow, do their job
2. In which stage do cells create 2 new nuclei each with a
copy of the same chromosomes as the parent cell
3. Which stage of the cell cycle does the cytoplasm divide
to create 2 separate cells that are genetically identical
4. If a cell has 8 chromosomes how many in the new cells?
5. Write the correct order of phases in Mitosis
5. What stage is this and what are the chromosomes doing?
Mitosis: Can you name the stages?
1
2
3
4
5
Mitosis: Can you name the stages?
Prophase
2
3
4
5
Mitosis: Can you name the stages?
Prophase
Metaphase
3
4
5
Mitosis: Can you name the stages?
Prophase
Metaphase
Anaphase
4
5
Mitosis: Can you name the stages?
Prophase
Metaphase
Anaphase
Telophase
5
Mitosis: Can you name the stages?
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
 Phases of mitosis - IPMATC
I
I
Passed
P
My
M
Algebra
A
Test
T
CHACHING!
C
Cell Cycle
 A typical cell goes
through a process of
growth, development,
and reproduction
called the cell cycle.
 Most of the cycle is
called interphase.
INTERPHASE
Cell Cycle
 The longest
phase in the cell
cycle is
interphase.
 The 3 stages of
interphase are
called G1, S, and
G2 .
Cell Cycle
 Cells spend most of
their time in G1: it is
the time when the
cell grows and
performs its normal
function.
 Control of cell
division occurs in G1:
a cell that isn’t
destined to divide
goes into G0.
Cell Cycle
 The S phase
(“Synthesis”)
is the time
when the
DNA is
replicated.
Parent strands
Daughter strands
Cell Cycle
 G2 is the period
between S and
mitosis.
 DNA replication
is checked and the
cell is getting
ready to divide.