Download Cell Regulation

Standard B 2.7: Cell Regulation
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Intro:
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(do not have to copy)
scientists observed healthy cells in petri dish
w/ nutrients
● cells divide rapidly
● stop dividing when come in contact w/ one
another
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ex: cut or broken bone-- cells grow 7 divide
more rapidly to heal body; when 'fixed,'
(cells touching each other) they stop
dividing
Cell Division is highly controlled
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Internal signals: chemicals (enzymes)
External signals: sense presence of chemical
(growth factor) produced in other cells
Cells respond to physical signals from envt.
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turn off: too closely packed/ touching
surface
 turn on: not in contact w/ surface
Cell Cycle Check Points
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def: critical control point where stop & go
signals can regulate cell cycle
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G1: healthy & large enough ?
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G2: check & correct mistakes in copied DNA
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large enough to divide ?
Mitosis checkpoint: metaphase chromosomes properly attached to spindle
fibers ?
Uncontrolled Cell Division
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LEADS TO CANCER! : *(
Cancer cells...
 do NOT heed normal signals
 divide when densely packed
and/or when no growth factor
present
CANCER
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Cancer begins w/ one faulty cell:
 body normally destroys damaged
cell
 if not, when it divides, produces
cancer cells
 no regulation --> uncontrolled
growth
TUMORS
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benign: mass of abnormal cells that remains
@ original site (does not move through body)
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can often be removed by surgery
malignant: mass of cells that invades &
impairs functions of one or more organs
Cancer cells can separate from tumor &
enter circulatory & lymphatic systems
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transplanted to invade other body parts
Standard B 2.4: Cell Differentiation
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Nearly all cells in multicell. org have same
chromosomes and DNA
differentiation = specific parts of DNA are
activated
 create
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different function & structure
all cells initially have potential to become
any type of cell
differentiation CANNOT be REVERSED
Stem Cells
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Unspecialized cells, continually reproduce
Ability to differentiate into 1 or more type of
specialized cells
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embryonic stem cells
 adult stem cells (bone marrow)
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Stem cell research:
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Scientists have demonstrated that stem
cells diff. into specialized cells (w/ right lab
culture conditions)
Cell Hierarchy
Websites
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NOVA:
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Video: How Cancer Spreads
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http://www.mayoclinic.com/health/cancer/MM00638
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HowStuffWorks Video-The Cell: Cell Differentiation
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http://www.pbs.org/wgbh/nova/cancer/grow_flash.html
http://videos.howstuffworks.com/hsw/10313-the-cell-cell-differentiationvideo.htm
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A Hard Sell on Stem Cells: Learning About Different Types of Stem Cells-
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http://learning.blogs.nytimes.com/2005/10/18/a-hard-sell-on-stem-cells/