CELL GROWTH

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CELL GROWTH DIVISION 10-1 10-2

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Cell Growth and Division

• Pre-assessment Quiz

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Cell Growth and Division

• Limits to Cell Growth
• 1. DNA Overload
• 2. Exchanging Materials
• 3. Ratio of Surface Area to Volume
• 4. Cell Division

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2 Reasons why cells divide
DNA OVERLOAD

• _____________________As cell grows bigger demand
  on DNAgenetic 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
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2 Reasons why cells divide
Material exchange cant keep up

• 2. _____________________As cell grows bigger, it
  gets harder to transport stuff across membranes

http//www.animationlibrary.com
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The ability to transport of oxygen, food, waste
across cell membrane depends on
_______________ How much of this stuff used
depends on ___________
SURFACE AREA
CELL VOLUME
As cell grows these DONT increase at the same
rate, volume increases faster than surface area
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• When cells get too big, they cant 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
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• 102 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

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DNA CAN BE
SPREAD OUT INNON-DIVIDING CELLS
SCRUNCHED UP IN DIVIDINGCELLS
CHROMATIN
CHROMOSOMES
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DNA in PROKARYOTES(Bacteria)

• BACTERIAL DNA is CIRCULAR
• HAVE ONE CHROMOSOME
• NO NUCLEUS ATTACHED TO CELL MEMBRANE

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DNA in EUKARYOTES(Plants Animals)

• DNA is ROD-SHAPED CHROMOSOMES
• MANY PAIRS
• FOUND IN NUCLEUS

http//cellbio.utmb.edu/cellbio/chrom2.jpg
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Chromosomes (scrunched up DNA)

• All organisms have specific numbers of
  chromosomes
• Humans _____ Chromosomes
• Fruit Flies 8 Chromosomes
• Carrots 18 Chromosomes

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Chromosome structure
CHROMATIDS

• ___________________ 2 identical arms
• __________________
• area that holds the chromatids together

CENTROMERE
HOMOLOGOUS

• __________________ PAIR
• A pair of chromosomes (2) (one from mom one
  from dad)

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HOMOLOGOUS CHROMOSOMES

• SAME SIZE
• SAME SHAPE
• CARRY GENES for the SAME TRAITS
• BUT _________________!
• Both have the same gene, but they dont have to
  be the same trait expressed
• Ex. Eye color
• might not have
• the same color
• of eyes

NOT IDENTICAL
http//arnica.csustan.edu/biol3020/cell_division/c
ell_division.htm
http//sps.k12.ar.us/massengale/genetics20tutoria
l.htm
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CELL DIVISION in PROKARYOTES

• Bacteria reproduce using
• __________________________________

BINARY FISSION
http//fig.cox.miami.edu/cmallery/150/mitosis/fis
sion.jpg
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Cell Cycle

• Interphase
• G1
• S
• G2
• Mitosis (M) phase
• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis

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CELL CYCLE

• 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

INTERPHASE
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CELL DIVISION

• Nucleus divides
• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis
• Cytoplasm divides
• G0 cell stops dividing (Ex nerve cell)

MITOSIS
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• INTERPHASE (G1 - S - G2)

In between divisionsCells are in this phase most
of the time Can see nucleus DNA spread out as
chromatin
Cant see chromosomes
DNA gets copied (S) Cell gets ready to
divide
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Prentice Hall

• PROPHASE
• 1st dividing phase

http//www.microscopy.fsu.edu/micro/gallery/mitosi
s/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
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• METAPHASE

Chromosomes line up in ___________
middle
Microtubules connect the centromere to the two
poles of the spindle
Images fromPearson Eduction Ince Publishing as
Pearson Prentice Hall http//www.microscopy.fsu.e
du/micro/gallery/mitosis/mitosis.html
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• ANAPHASE

Centromeres split and the centrioles pull the two
sister chromatids _______ Anaphase ends when the
movement stops
apart
Images fromPearson Eduction Ince Publishing as
Pearson Prentice Hall http//www.microscopy.fsu.e
du/micro/gallery/mitosis/mitosis.html
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• TELOPHASE

two
See ______ nuclei
Nuclear envelope nucleolus return Chromosomes
spread back out as chromatin Centrioles
disappear Spindle fibers break and disappear
Images fromPearson Eduction Ince Publishing as
Pearson Prentice Hall http//www2.bc.cc.ca.us/cnew
ton/Biology2011/Mitosis.html
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CYTOKINESIS Cytoplasm splits into 2 cells

ANIMAL CELLS pinch cytoplasm in two with a
______________________
CLEAVAGE FURROW
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CYTOKINESIS Cytoplasm splits into 2 cells

PLANT CELLS cant pinch because they have a
sturdy ____________ Plant cells separate
cytoplasm by growing a _______________ down the
middle.
CELL WALL
CELL PLATE
http//www.eastcentral.edu/acad/depts/BI/plant_mit
osis_nolabels.html
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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/sup
  plements/nih1/cancer/activities/activity2_animatio
  ns.htm

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Concept Map
Section 10-2
Cell Cycle
includes
is divided into
is divided into
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Concept Map
Section 10-2
Cell Cycle
includes
is divided into
is divided into
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REGULATING the CELL CYCLE
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Regulating the Cell Cycle

• Controls on Cell Division
• Cell Cycle Regulators
• 1. Internal Regulators
• 2. External Regulators
• Uncontrolled Cell Growth

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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.
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• 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 dont divide once they
form (nerve cells)
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• CELL CYCLE REGULATORS

In early 1980s scientists discovered aprotein
in dividing cells that caused a ______________to
form in _______________ cells
Mitotic spindle
NON-dividing
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Prentice Hall
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• CELL CYCLE REGULATORS

Levels of this protein rose and fell with the
cell cycle so it was named __________ because it
seemed tocontrol the cell cycle. A whole family
ofCYCLINS have since beendiscovered that
regulate the_____________________ in EUKARYOTIC
CELLS
CYCLIN
TIMING of CELL CYCLE
Pearson Education Inc Publishing as Pearson
Prentice Hall
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• OTHER REGULATORS

INTERNAL
______________ REGULATORSProteins that respond
to events inside the cell. They allow cell cycle
to proceed only if certain processes have
happened EX Cell cant enter mitosis until all
the chromosomes have been copied
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• OTHER REGULATORS

EXTERNAL
______________ REGULATORSProteins 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/ta
il_HumanTail.gif
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• EXTERNAL REGULATORS

Molecules on the surface of neighboring cells act
as signals to slow down or stop the cells
cycle. These signals prevent excessive growth
and keep tissues from disrupting each other.
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Prentice Hall
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• NO CONTACT INHIBITION

Cancer cells have lost control of their cell
division genes they dont stop growing when
they touch nearby cells. . . they just keep
growing! Thats what makes a tumor.
http//www.exn.ca/news/images/2000/08/02/20000802-
cancer.jpg
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Cancer cells

• Dont stop dividing
• Like a car with no brakes
• Can spread to new places
• by entering the bloodstream (METASTASIS)
• ______________ are substances that can damage DNA
  and cause cancer
• Ex Cigarette smoke (OR CHEW), Radiation,
  chemicals in environment, even viruses,

Carcinogens
http//www.dfci.harvard.edu/abo/news/publications/
pop/fall-winter-2004/images/metastasis_1.jpg
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Cancer cells

• Cancer is complicated and can have many
• causes, but all cancers have one thing in
  common.
• They have lost control over their _____________.
• Many cancers cells have a damaged or defective
• gene called _____, so they cant respond to
• normal cell signals to control their growth.

CELL CYCLE
p53
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Cancer
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• Animation 1 http//science.education.nih.gov/sup
  plements/nih1/cancer/activities/activity2_animatio
  ns.htm

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