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CELL GROWTH
& DIVISION
10-1 & 10-2
Cell Growth and Division
 Pre-assessment Quiz
Cell Growth and Division
 Limits to Cell Growth
1. DNA “Overload”
 2. Exchanging Materials
 3. Ratio of Surface Area to
Volume
 4. Cell Division

2 Reasons why cells divide
DNA OVERLOAD
1. _____________________
As cell grows bigger demand on DNA
“genetic library” becomes too great
Ex: Small town library has 1000 books.
As town grows and more people
borrow books, there may be a
waiting list to read the
most popular titles
http://www.adc.state.az.us/images/Off-Library.JPG
2 Reasons why cells divide
exchange can’t keep up
2. Material
_____________________
As cell grows bigger, it gets harder to
transport “stuff” across membranes
http://www.animationlibrary.com
The ability to transport of
oxygen, food, waste across cell
membrane depends on
SURFACE AREA
_______________
How much of this “stuff” used
CELL VOLUME
depends on ___________
As cell grows these DON’T increase at the same
rate, volume increases faster than surface area
When cells get too big, they can’t
transport “stuff” fast enough, or in big
enough amounts.
So cells grow by dividing into many, small
cells instead of growing few, bigger cells.
http://www.animationlibrary.com
10–2
Cell Division
A. Chromosomes
B. The Cell Cycle
C. Events of the Cell Cycle
D. Mitosis
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
E. Cytokinesis
DNA CAN BE:
SPREAD OUT IN
NON-DIVIDING
CELLS
CHROMATIN
SCRUNCHED UP
IN DIVIDING
CELLS
CHROMOSOMES
DNA in PROKARYOTES
(Bacteria)
 BACTERIAL DNA is CIRCULAR
 HAVE ONE CHROMOSOME
 NO NUCLEUS;
ATTACHED TO CELL MEMBRANE
DNA in EUKARYOTES
(Plants & Animals)
 DNA is ROD-SHAPED CHROMOSOMES
 MANY PAIRS
 FOUND IN NUCLEUS
http://cellbio.utmb.edu/cellbio/chrom2.jpg
Chromosomes
(scrunched up DNA)
 All organisms have specific numbers
of chromosomes
46 Chromosomes
= _____
 Fruit Flies = 8 Chromosomes
 Carrots = 18 Chromosomes
 Humans
Chromosome structure
CHROMATIDS
 ___________________
2 identical arms
CENTROMERE
 __________________
area that holds the
chromatids together
HOMOLOGOUS
•__________________
PAIR
A pair of chromosomes (2)
(one from mom; one from dad)
HOMOLOGOUS CHROMOSOMES
 SAME SIZE
 SAME SHAPE
 CARRY GENES for the SAME
TRAITS
NOT IDENTICAL
 BUT _________________!


Both have the same gene, but
they don’t have to be the same
trait expressed
Ex. Eye color
might not have
the same color
of eyes
http://arnica.csustan.edu/biol3020/cell_division/cell_division.htm
http://sps.k12.ar.us/massengale/genetics%20tutorial.htm
CELL DIVISION in PROKARYOTES
Bacteria reproduce using
BINARY FISSION
__________________________________
http://fig.cox.miami.edu/~cmallery/150/mitosis/fission.jpg
Cell Cycle
 Interphase
G1
 S
 G2
 Mitosis (M) phase






Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
CELL CYCLE
INTERPHASE – “in between” division
G1- Gap phase 1, Cell Growth
Cell Growth, increase size
Cell is “doing its job”
DNA is spread out as chromatin
S – Synthesis phase
Chromosomes are copied
G2- Gap phase 2, Prepare for Mitosis
Cell growth, get ready for cell division by
producing organelles & molecules
CELL DIVISION
MITOSIS – Nucleus divides
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis –
Cytoplasm divides
G0 – cell stops dividing
(Ex: nerve cell)
INTERPHASE (G1 - S - G2)
In between divisions
Cells are in this phase most of the time
Can see nucleus
DNA spread out as chromatin
Can’t see chromosomes
DNA gets copied (S)
Cell gets ready to divide
PROPHASE
Pearson Education Inc publishing as Pearson Prentice Hall
1st dividing phase
http://www.microscopy.fsu.edu/micro/gallery/mitosis/mitosis.html
Chromosomes appear (scrunched up X shape)
Centrioles appear in & move to opposite poles
of the nucleus
Spindle fibers form & attach to chromosomes
to help them separate
Nuclear membrane & nucleolus disappear
METAPHASE
Chromosomes line up in
___________
middle
Microtubules connect the
centromere to the two poles
of the spindle
Images from:
Pearson Eduction Ince; Publishing as Pearson Prentice Hall
http://www.microscopy.fsu.edu/micro/gallery/mitosis/mitosis.html
ANAPHASE
Centromeres split and the centrioles pull
apart
the two sister chromatids _______
Anaphase ends when the movement stops
Images from:
Pearson Eduction Ince; Publishing as Pearson Prentice Hall
http://www.microscopy.fsu.edu/micro/gallery/mitosis/mitosis.html
TELOPHASE
two nuclei
See ______
Nuclear envelope & nucleolus return
Chromosomes spread back out as chromatin
Centrioles disappear
Spindle fibers break and disappear
Images from:
Pearson Eduction Ince; Publishing as Pearson Prentice Hall
http://www2.bc.cc.ca.us/cnewton/Biology%2011/Mitosis.html
CYTOKINESIS
Cytoplasm splits into 2 cells
ANIMAL CELLS pinch cytoplasm in two
CLEAVAGE FURROW
with a ______________________
CYTOKINESIS
Cytoplasm splits into 2 cells
PLANT CELLS can’t pinch because
CELL WALL
they have a sturdy ____________
Plant cells separate cytoplasm by growing a
CELL PLATE
_______________
down the middle.
http://www.eastcentral.edu/acad/depts/BI/plant_mitosis_nolabels.html
Cell Cycle Video
 http://www.cellsalive.com/mitosis.htm
 http://sciencevideos.wordpress.com/2007/09/
24/the-cell-cycle-mitosis/
 Animation 2:
http://science.education.nih.gov/supplements/
nih1/cancer/activities/activity2_animations.ht
m
Concept Map
Section 10-2
Cell Cycle
includes
is divided into
is divided into
Concept Map
Section 10-2
Cell Cycle
includes
G1 phase
Interphase
M phase
(Mitosis)
is divided into
is divided into
S phase
G2 phase
Prophase
Metaphase
Anaphase
Telophase
REGULATING the
CELL CYCLE
Regulating the Cell Cycle
 Controls on Cell Division
 Cell Cycle Regulators
1. Internal Regulators
 2.
External Regulators
 Uncontrolled Cell Growth

Controls of Cell Division
Cells in a petri dish will continue to grow until they
touch other cells.
Cells in our bodies will do the same thing.
Ex. A finger that stops bleeding.
CELL DIVISION GENES
Some cells divide frequently
(some human skin cells divide once/hour)
Some cells divide occasionally
(liver cells divide about once/year)
Some cells don’t divide once they form
(nerve cells)
CELL CYCLE REGULATORS
In early 1980’s scientists discovered a
protein in dividing cells that caused a
Mitotic spindle
______________to
form in
NON-dividing
_______________
cells
Pearson Education Inc; Publishing as Pearson Prentice Hall
CELL CYCLE REGULATORS
Levels of this protein rose and fell with
the cell cycle so it was named
CYCLIN
__________
because it seemed to
control the cell cycle.
A whole family of
CYCLINS have since been
discovered that regulate the
TIMING of CELL CYCLE
_____________________
in EUKARYOTIC CELLS
Pearson Education Inc; Publishing as Pearson Prentice Hall
OTHER REGULATORS
INTERNAL
______________
REGULATORS
Proteins that respond to events inside
the cell. They allow cell cycle to proceed
only if certain processes have happened
EX: Cell can’t enter mitosis
until all the chromosomes
have been copied
OTHER REGULATORS
EXTERNAL
______________
REGULATORS
Proteins that respond to events outside
the cell. Signals tell cell to speed up or
slow down the cell cycle
EX: Growth factors stimulate cells to
divide. Especially important
during wound healing
and embryo development
http://www.suite101.com/files/topics/6234/files/tail_HumanTail.gif
EXTERNAL REGULATORS
Molecules on the surface of neighboring
cells act as signals to slow down
or stop the
cell’s cycle.
These signals prevent
excessive growth and
keep tissues from
disrupting each other.
Pearson Education Inc; Publishing as Pearson Prentice Hall
NO CONTACT INHIBITION
Cancer cells have lost control of their
cell division genes – they don’t stop
growing when they touch nearby
cells. . .
they just keep
growing!
That’s what makes
a tumor.
http://www.exn.ca/news/images/2000/08/02/20000802-cancer.jpg
Cancer cells
 Don’t stop dividing
 Like a “car with no brakes”
 Can spread to new places
by entering the bloodstream
(METASTASIS)
Carcinogens are substances that can
 ______________
damage DNA and cause cancer
Ex: Cigarette smoke (OR CHEW),
Radiation, chemicals in environment,
even viruses,
http://www.dfci.harvard.edu/abo/news/publications/pop/fall-winter-2004/images/metastasis_1.jpg
Cancer cells
Cancer is complicated and can have many
causes, but all cancers have one thing in
common.
They have lost control over their
CELL CYCLE
_____________.
Many cancers cells have a damaged or defective
p53 so they can’t respond to
gene called _____,
normal cell signals to control their growth.
Cancer
 Animation 1:
http://science.education.nih.gov/supplements/ni
h1/cancer/activities/activity2_animations.htm
ANTI-SMOKING commercial