Cell Division
Mitosis: the process by which cells
reproduce themselves, resulting in
daughter cells that contain the same
amount of genetic material as the parent
cell.
Simply put…how one cell becomes two
• Cell Division refers to the ENTIRE process
• Mitosis is a phase of the cell cycle
• Mitosis, itself, has four phases (Prophase,
Metaphase, Anaphase, Telophase)
Animated Mitosis Cycle
http://www.cellsalive.com/mitosis.htm
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis
Cell Type
Life Cycle
(how often they go through Mitosis)
Intestine lining
Every 2-3 days
Stomach lining
Every 5 days
Skin cells
Every 28 days
Liver cells
Every 42 days
Bone cells
Every 90 days
Red blood cells
Every 120 days
OUR BODIES MAKE 1,000,000,000 (ONE
BILLION) CELLS EVERY DAY????
 OUR CELLS ARE CONSTANTLY DIVIDING.
 MITOSIS IS HOW WE MAKE NEW CELLS,
AND GET RID OF OLD, DEAD CELLS.

The Cell Cycle (aka Cell
Division and Mitosis) is how
we make new body cells.
Our body cells are called
“somatic” (SO-mat-TICK)
All cells in our body (somatic
cells) reproduce through
MITOSIS, except our GAMETES
(or sex cells)—meaning
sperm or eggs. Sperm and
eggs reproduce through
MEIOSIS
 Has
3 phases
 G1 (growth)
 S (DNA synthesis, DNA replication)
 G2 (growth)
A
cell spends 75% (3/4) of its life
in Interphase
Chromosomes are copied (# doubles)
• Chromosomes appear as threadlike coils
(chromatin) at the start, but each chromosome
and its copy(sister chromosome) change to sister
chromatids at end of this phase
•
Nucleus
CELL
MEMBRANE
Cytoplasm
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
•
•
Mitosis begins (cell PREPARES to divide)
Centrioles (or poles) appear and begin to
move to opposite end of the cell.
Sister Chromatids become visible.
Sister chromatids
Centrioles
Spindle fibers
Animal Cell
Plant Cell
Spindle fibers
Centrioles
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Chromatids (or pairs of chromosomes) attach
to the spindle fibers in the MIDDLE of the cell.
Centrioles
Spindle fibers
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Chromatids (or pairs of chromosomes)
separate and begin to move to opposite
ends of the cell. Chromatids pull APART
Centrioles
Spindle fibers
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
•
•
Two new nuclei form.
Chromosomes appear as chromatin (threads
rather than rods).
Mitosis ends.
Nuclei
Chromatin
Nuclei
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Cell membrane moves inward to create two
daughter cells – each with its own nucleus
with identical chromosomes.
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
21
- Cell Division
23
23
Count the number of cells in each stage
Stage
Interphase
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Cytokinesis
Percent
time in
each
stage
•
•
•
•
•
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It’s important that cells have a cycle of growth
and death.
Some cells fail to die and continually divide
(Mitosis)
Cells that continually divide and continue to
build up.
This is called a tumor
A malignant tumors is cancerous.
A benign tumor is non-cancerous.
•
•
•
If cells do not die, cancer is likely to develop (as the
result tumors)
So, if cells continue to divide (undergo Mitosis), tumors
and cancer will develop.
Apoptosis (programmed cell death) is necessary. A
person’s health could be a stake if there is an error in
Mitosis and cells fail to die.
•
•
•
These images are examples of
tumors.
Cancer can take place on
any part of the body.
The entire body is made of
cells, and cancer starts with
cells
Raise Cancer
Awareness!
•
•
Genetics (heredity): some cancers are passed
along family lines (breast cancer, prostate cancer)
Diet and obesity: colon cancer is caused by those
who consume a diet high in fat
Environmental factors:
2nd hand smoking-those who do not smoke can also
get cancer because of those who smoke around
them
•
Sun/UV rays: extended exposure to UV rays can
cause skin cancer (melanoma)
http://www.cellsalive.com/mitosis.htm
Watch the animation! See how one cell divides into two!
•
•
•
Males make sperm; females make
eggs
Males go through meiosis until they are
in their 70s (men make sperm until they
are elderly)
Ladies are born with the number of
eggs they will have until menopause
• Meiosis is how the body makes more
gametes (sex cells).
• Meiosis is NOT sexual reproduction.
• Simply put, Meiosis is how we make sperm
or eggs
Mitosis
Meiosis
# of daughter cells
2
4
# of divisions
1
2 (Meiosis I & II)
Chromosome number
Diploid (2n). Daughter
cells have the same
number of
chromosomes as the
parent cell
Haploid (n). Daughter
cells have half the
number of
chromosomes as
parent cell.
# of phases
4-P, M, A, T
8-11, Interphase, P1,
M1, A1, T1, P2, M2, A2,
T2
Type of cells produced Somatic (body cells)
Gametes (sex cells)




Mitosis – diploid (2n)
Cells that divide and
reproduce by
MITOSIS are diploid.
They have the same
# of chromosomes
as the parent cell
Ex. If my liver cell has
46 chromosomes,
the daughter cells
will have 46
Meiosis – Haploid (n)
Cells that divide and
reproduce by MEIOSIS are
HAPLOID.
 They have half the
number of chromosomes
as the parent cell.
 Ex. If an egg cell with 46
chromosomes goes
through meiosis, the
daughter cells will have
23 chromosomes



Cells that are diploid
reproduce by
Mitosis.
Example: a Liver cell
that is reproducing
through mitosis has
46 chromosomes.
After Mitosis, the new
daughter cells have
46 chromosomes.



Cells that are
haploid reproduce
by Meiosis.
Example: A man’s
sperm has 46
chromosomes. After
it goes through
Meiosis, the
daughter cells have
23
Gametes (sex cells)
are HAPLOID (half)



Somatic = body cell
Mitosis
Diploid (2n)
Organism



Gamete = sex cell
Meiosis
Haploid (n)
Somatic Cell
(Mitosis/Diploid) 2n
Gamete (Meiosis/Haploid)
n
Human
46
23
Garden pea
14
7
Fruit fly
8
4
Tomato
24
12
Dog
78
39
Chimpanzee
48
24
Leopard frog
26
13
Corn
20
10