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MITOSIS UNIT
Chapter 10; Cell Growth and Division
Prentice Hall Biology
How do little puppies grow up?
When I get a cut, how do I heal?

DNA: DeoxyriboNucleic Acid—The
genetic material of all of life! DNA is
made up of nucleotides, and is the basis
of all natural heredity traits of an
organism.

Prokaryotes- ‘Simple’ one-celled
organisms that do not have a nucleus.
› Bacteria and Archeabacteria.

Eukaryotes- ‘Higher’ organisms that have
a nucleus and a more complete DNA.

Centriole —Organelles found in animal cells that
help with the process of mitosis

Centromere —The area where sister chromatids
are held together.

Homologous Chromosome — A pair of similar
chromosomes. In most organisms, one of these
chromosomes came from the father, and the
other chromosome came from the mother.

Sister Chromatid —A sister chromatid is two
copies of the same DNA sequence, held
together by a centromere.

Chromatin — A thread-like mass of DNA seen in the
nucleus during most of the a cell’s life

Chromosome — a rod-like bundle of DNA seen
during mitosis.

Mother Cell — A cell that is about to divide by
mitosis.

Daughter Cells — The two cells that result from
mitosis. Daughter cells will have identical DNA
to each other, which is the same DNA that the
mother cell had.

Mitosis is the process of asexual cell
division.
› Mitosis brings about growth & development
› Mitosis enables healing when we get cut.

Mitosis creates two identical cells from
one cell.
› Each cell will have a full copy of the original
DNA.
Wouldn’t it be easier to just have fewer and larger cells?
Cells are bustling with activity! They need
proteins and smaller inorganic compounds
to come in to and move out of the cell. They
use these resources all throughout the cell,
and every organelle needs to have access to
these resources.
Wouldn’t it be easier to just have fewer and larger cells?
If a cell becomes bigger, the ratio of its
surface area to its volume decreases. With
a poorer ratio, resources can’t move into the
cell quick enough to reach all of organelles.
Wouldn’t it be easier to just have fewer and larger cells?
Also:
There is only one area in the cell where
there is DNA, yet all of the cell needs the
proteins that are made from the DNA. If a
cell becomes too large, the demand on
the DNA to copy the necessary genes
for all of the cell to function becomes
too great.
•
•
•
Interphase is made up of the G1, S, and G2
phases of the cell cycle.
During this phase, chromosomes are copied.
Chromosomes appear as threadlike coils
(chromatin) during this phase.
Nucleus
Cell Membrane
Cytoplasm
The Cell Cycle

Interphase is made up
of the G1, S, and G2
phases of the cell cycle.
M
Phase
G2
Phase
S
Phase
G1
Phase
Animal Cell
Plant Cell
The nuclear membrane breaks down.
• The chromatin condenses, and chromosomes
become visible
• Centrioles appear and begin to move to
opposite end of the cell.
• Spindle fibers form between the centrioles.
•
chromosomes
Nuclear membrane
Centrioles
Spindle fibers
Animal Cell
Spindle fibers
Plant Cell
Sister chromatids line up at the mid-line of the
cell.
• Centromeres (the area where the sister
chromosomes are held together) attach to
the spindle fibers.
•
Centrioles
Spindle fibers
Animal Cell
Plant Cell
Spindle fibers pull apart the centromeres of
the sister chromatids.
• Each centriole pulls one of the sister
chromatids to its pole.
•
Centrioles
Spindle fibers
Animal Cell
Plant Cell
•
•
•
•
Two new nuclear membranes form.
Chromosomes begin to appear as chromatin
(threads rather than rods).
Spindle fibers break down.
Mitosis ends.
Nuclear
Membrane
Chromatin
forming
Nuclear
Membrane
Animal Cell
Plant Cell
•
In animals: cell membrane pinches inward to
create two daughter cells – each with its own
nucleus with identical chromosomes.
•
In plants: a cell wall forms between the newly
divided cells.
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
A short film on mitosis.
Mitosis animation
Cell animations
The Cell Cycle

Mitosis is a very
controlled process
that only occurs in
a small fraction of
the cell’s life
M
Phase
G2
Phase
S
Phase
G1
Phase
How do little puppies grow up?
Mitosis is the process that allows living things to
grow. Without mitosis we wouldn’t ever grow
and develop. So if we were to stop the mitosis
in this puppy, we would be preventing it from
ever getting any bigger.
When I get a cut, how do I heal?
Mitosis is involved in healing after an injury.
If we get a cut or a scrape, our body
uses mitosis to heal itself.
Every type of organism must grow and develop and
then reproduce in order to continue the species.
For eukaryotes, mitosis is the process by which
organisms grow and develop. A hallmark of higherorder life is having a multi-cellular body, but since
reproduction gives only a single fertilized cell, the cell
must divide over and over again in order to make an
organism. Mitosis is the process across all of the
eukaryotic kingdoms by which this growth and
development occurs.
On a half-sheet of paper, answer these questions:
1. How could you describe the cells that result from Mitosis?
1. They contain no organelles.
2. They are the same as the cell prior to mitosis.
3. They contain half of the amount of DNA of the original cell.
4. They must be either plant or animal cells.
2. What are the four main stages of Mitosis?
1.
2.
3.
4.
On a half-sheet of paper, answer these questions:
3. Describe what happens during interphase:
4. Describe the role of spindle fibers in mitosis. In what stage do
they appear? Where do they connect to? When do they
disappear?
The Cell Cycle

The duration of the
cell cycle varies in in
different organisms,
different tissues, and
at different points in
development, but it is
a very controlled
process.
M
Phase
G2
Phase
S
Phase
G1
Phase

The cell cycle is regulated by a protein
called cyclin.

The cell cycle is also regulated with ‘Internal
regulators.’

The cell cycle is also regulated by ‘external
regulators.’

If a cell has too many cyclins, if the internal
regulators fail, or if there are external
regulators that are constantly signaling for
mitosis to occur, a cell will continue to
divide without stopping.

A scenario where a cell is continually
dividing when it shouldn’t be is called
uncontrolled cell growth.