Regents Biology 2006-2007 Cell Membranes & Movement Across Them.
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Transcript of Regents Biology 2006-2007 Cell Membranes & Movement Across Them.
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Regents Biology 2006-2007
Cell Membranes&
Movement Across Them
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Regents Biology
Cell (plasma) membrane Cells need an inside & an outside…
separate cell from its environment cell membrane is the boundary
INfood- sugars- proteins- fats
saltsO2
H2O
OUTwaste- ammonia- salts- CO2
- H2O products- proteins
cell needs materials in & products or waste out
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Regents Biology
Lipids of cell membrane Membrane is made of special kind of lipid
phospholipids “split personality”
Membrane is a double layer phospholipid bilayer
inside cell
outside cell
lipid
“repelled by water”
“attracted to water”
phosphate
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Regents Biology
Semi-permeable membrane Cell membrane controls what gets in or out Need to allow some materials — but not all
— to pass through the membrane semi-permeable
only some material can get in or out
aa H2Osugar lipids salt waste
So what needs to get across the membrane?
O2
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Regents Biology
Cell membrane channels Need to make “doors” through membrane
protein channels allow substances in & out specific channels allow specific material in & out H2O channel, salt channel, sugar channel, etc.
inside cell
outside cell
sugaraaH2O
saltwaste
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Regents Biology
Protein channels Proteins act as doors in the membrane
channels to move specific molecules through cell membrane
HIGH
LOW
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Regents Biology
Molecules move from high to low Diffusion
move from HIGH to LOW concentration
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Regents Biology
Diffusion Move from HIGH to LOW concentration
passive transport no energy needed
diffusion osmosis
diffusion of water
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Regents Biology
Diffusion Move from HIGH to LOW concentration
directly through membrane simple diffusion no energy needed
help through a protein channel facilitated diffusion (with help) no energy needed HIGH
LOW
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Regents Biology
Simple vs. facilitated diffusion
inside cell
outside cell
lipidinside cell
outside cell
H2O
simple diffusion facilitated diffusion
H2O
protein channel
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Regents Biology
Active transport Cells may need molecules to move against concentration “hill” need to pump “uphill”
from LOW to HIGH using energy protein pump requires energy
ATP
ATP
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Regents Biology
Transport summary
simplediffusion
facilitateddiffusion
activetransport
ATP
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Regents Biology 2006-2007
OsmosisMovement of Water Across Cell Membrane
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Regents Biology
Osmosis Water is very important, so we talk about
water separately Osmosis
diffusion of water from HIGH concentration of water to LOW concentration of water across a semi-permeable membrane
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Regents Biology
Keeping right amount of water in cell Hypotonic condition
a cell in distilled water high concentration of water
around cell cell gains water
problem: cells gain water, swell & can burst
Plant cells- become turgid, which which is normal
Animal cells-burst and die
freshwater
No problem,here
KABOOM!
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Regents Biology
Keeping right amount of water in cell Isotonic condition
no difference in concentration of water between cell & environment
Water flows equally into and out of cell cell in equilibrium Plant cells: Flaccid Animal cells: Normal
balanced
I couldbe better…
That’sbetter!
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Regents Biology
Keeping right amount of water in cell Hypertonic solution
a cell in salt water low concentration of water
around cell cell loses water
Plant cells- shrink, can survive for a time
Animal cells- shrink
and die
saltwater
I willsurvive!
I’m shrinking,I’m shrinking!
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Regents Biology
Ice Fishing in Barrow