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CELL DIVISION
Life Science
How do little elephants grow up
to be BIG elephants?
WHY DO ANIMALS SHED THEIR SKIN?
CELL DIVISION
Cell division: increases the number of cells and causes manycelled organisms to grow.
The new cells that are formed are called: daughter cells
Life cycles: periods of formation, growth and development
Nucleus: control center of the cell. Contains DNA
DNA makes up a Chromosome
genes
Why do cells divide?
1) Reproduction
2) Growth
3) Repair
How does the cell know how to divide?
The DNA has the instructions
for all of the cell’s activities.
The sequence of development
and division of a cell
3 Parts
1. Interphase - Preparation
2. Mitosis – Cell division
3. Cytokinesis – Splitting
How long does it take?
 Adult human cell: ~24 hrs
• 18-20 hours in
interphase
• 2 hours in mitosis
Animated Cell Cycle
http://www.cellsalive.com/mitosis.htm
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis
Stage
Definition Picture
1. Interphase
(I)
NOT part of
mitosis
-chromosomes
replicates
-cell grows +
rests
Diagram
INTERPHASE
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Stage
Definition Picture
1. Interphase
(I)
NOT Part of
mitosis
-Chromosomes
replicate
-cell grows +
rests
2. Prophase
(Play)
-nuclear
membrane and
nucleolus
disappears
-spindle
fibers start to
form from
centrioles
Diagram
Centromere
Chromosome
Centriole
Spindle
Fiber
PROPHASE
Animal Cell
Plant Cell
Spindle fibers
Chromosome
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
3. Metaphase
(More)
-double
chromosomes
attach to spindle
Chromosomes
Spindle
-line up at
equator (middle)
Centriole
Spindle
METAPHASE
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
3. Metaphase
(More)
-double
chromosomes
attach to spindle
-line up at
equator (middle)
4. Anaphase
(At)
-chromosomes
separate towards
ends of cell
Chromatid
Spindle
Centriole
ANAPHASE
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
3. Metaphase
(More)
-double
chromosomes
attach to spindle
-line up at
equator (middle)
4. Anaphase
(At)
-chromosomes
separate towards
ends of cell
5. Telophase
(The)
-chromosomes
reach opposite
sides
-cytoplasm
divides
(cytokinesis)
(Circus)
Cell Plate
Cleavage
Furrow
Nuclear
Chromosomes Membrane
TELOPHASE
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
REMEMBER!
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
IPMATC
I Play More At The Circus
BUT WHY DO CELLS DO THIS?
RESULTS OF MITOSIS
1. Produces two identical daughter cells
2. Daughter cells will have exactly the same number
of chromosomes as the parent cell
Ex. Human body cells have 46
chromosomes
3. This is a form of asexual reproduction
PLANT CELL MITOSIS VS ANIMAL CELL MITOSIS
Plant cell Mitosis
Cytokinesis
(cytoplasm divides)
Centrioles
(spindle)
Cell
plate
Cleavage
furrow
Animal Cell Mitosis
PLANT CELL MITOSIS VS ANIMAL CELL MITOSIS
Cytokinesis
(cytoplasm divides)
Plant cell Mitosis
Animal Cell Mitosis
Cell plate
Cleavage furrow
Centrioles
(spindle)
Cell
plate
Cleavage
furrow
PLANT CELL MITOSIS VS ANIMAL CELL MITOSIS
Plant cell Mitosis
Animal Cell Mitosis
Cytokinesis
(cytoplasm divides)
Cell plate
Cleavage furrow
Centrioles
(spindle)
Not present
Present + asters
Cell
plate
Cleavage
furrow
CANCER
Cancer is uncontrolled cell division/cell growth
Factors damaging genes that may lead to cancer:
1. Ultraviolet (UV) radiation
2. Chemicals/pollutants
3. Airborne particles (asbestos)
4. Diet
5. Radioactivity
ASEXUAL REPRODUCTION
Asexual Reproduction:
Forms new organisms
Involves one parent
Genetic information identical to
parent
Ex. If mom has 12 chromosomes, baby
has 12 chromosomes
BENEFITS:
DISADVANTAGES:
Method
Definition
Binary Fission Parent cell
Examples
Amoeba
divides into
2 equal size
daughter
Cells
http://www.youtu Euglena
be.com/watch?v=
3cD3U2pgb5w
Bacteria
Method
Definition
Binary Fission Parent cell
divides into
2 equal size
daughter
cells
Budding
Parent cell
divides into
2 unequal size
daughter cells
http://www.youtube.com
/watch?v=JZLHJZZZS-Y
Examples
Amoeba
Bacteria
Euglena
Yeast
Hydra
Hydra
Method
Definition
Example
Sporulation
1,000’s of
specialized
cells that
burst from a
spore case
Bread Mold
http://www.youtube.co
m/watch?v=OrKr
QI8Grb0
Mushroom
Method
Definition
Example
Sporulation
1,000’s of
specialized
cells that
burst from a
spore case
Bread Mold
Mushroom
Regeneration
http://www.youtube.com
/watch?v=f7cXeWxxfD4
Ability to regrow body
Parts
-some re-grow
parts
-some re-grow
new
organisms
Parts-
Whole OrganismPlanaria
Salamander/
lizard tail, lobster Starfish from one leg
claws, starfish
and part of eye
legs
Method
Definition
Natural
Artificial
Vegetative
Propagation
Asexual
reproduction
in plants
involves roots,
stems, and
leaves
a. Tuber-white
potatoes
e. Grafting-apples
b. Bulb-tulip
f. Layeringraspberries
Natural and
Artificial
c. Runnerstrawberry
d. Rhizome-iris
g. Cutting-spider
plant
MEIOSIS: SEXUAL REPRODUCTION
 Formation
of sex
cells: sperm and egg
 Sex cells have half
the number of parent
cells
Ex. In humans sex cells
have 23 chromosomes
not 46 like all the other
cells
Why?
2 divisions
4 cells are produced
BENEFITS:
DISADVANTAGES:
MEIOSIS – TWO DIVISIONS OF THE NUCLEUS
Parent Cell
1st Division
2nd Division –
4 new daughter
cells with ½ the #
of chromosomes
FERTILIZATION
Fertilization: the joining of an egg and a sperm from
2 different organisms of the same species
The cell that forms from fertilization is called the
zygote.
Fertilization restores the number back to 46.