Download Selectively Permeable

11/15/2012
Selectively Permeable
 What did the strainer allow to pass through?
 If the strainer is “permeable” to water & sugar, what
does permeable mean?
 What could not pass through the strainer?
 If the strainer is “impermeable” to pennies &
paperclips, what does impermeable mean?
 What do you think selectively permeable means?
 What about semi-permeable?
Homeostasis
 Homeo = same
 Stasis = condition
A biological balance
A process in which organisms maintain
an internal balance (equilibrium)
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Cell Membrane
Proteins
Protein
Channel
Carbohydrate
Chains
Lipid
Bilayer
Lipid Bilayer
+
_
 Phosphate head is polar
 Hydrophilic end
 Fatty Acid tails are nonpolar
 Hydrophobic end
Hydro = water
Phobic = fear
Phillic = loving
Solutions
 What does the sugar/food coloring represent?
 Solute
 What does the water represent?
 Solvent
 Which solution has a greater concentration of solute?
 Which solution has more solvent?
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Solutions
 Hyper = above (high)
 Iso = same (equal)
 Hypo = below (low)
 Tonic = strength
 Hypertonic?
 Hypotonic?
 Isotonic?
 Diffusion of WATER (solvent) across a selectively
permeable membrane
Osmosis
Hypertonic
• Above/High
• Solution with the higher
concentration of solute
Isotonic
• Same/Equal
• Solutions have the same
concentration of a solute
• Below/Low
• Solution with the lower
concentration of solute
Hypotonic
Osmosis
 What happens to cells placed in an isotonic solution?
 Water moves in & out equally; stay same size
 What happens to cells placed in a hypertonic
solution?
 Water moves out of cell
 Animal cells shrink; Plant cells shrink or wilt
 What happens to cells placed in a hypotonic
solution?
 Water moves into cell
 Animal cells swell & may burst; Plant cells become more rigid
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Osmosis
TAKES NO ENERGY!!
Active Transport
Passive Transport
 Process that requires energy
 Process that does NOT
to move materials across cell
membranes against a
concentration gradient
requires energy to move
materials across cell
membranes against a
concentration gradient
Diffusion
 How long did it take you to detect the odor?
 How did the smell get from the balloon to your
nose?
 How do you think the molecules of the vanilla
travel from the balloon to your nose? Straight line,
zig zag?
 Diffusion – movement of PARTICLES
(solute) from a region of high concentration
to a region of low concentration
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Diffusion in Air
Diffusion in Water
Facilitated Diffusion
Movement of molecules across a membrane
through protein channels
TAKES NO ENERGY!!
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Passive Transport
Osmosis
Diffusion
Facilitated Diffusion
Endocytosis
endo = inside
cyto = cell
osis = process
A process in which a
cell takes materials in by
mmembrane folding
ENERGY NEEDED
Endocytosis
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Exocytosis
exo = outside
cyto = cell
osis = process
A process in which a
cell removes large
amounts of materials
ENERGY NEEDED
Active Transport
Endocytosis
Exocytosis
Transport Animations
Molecule Transport Across Cell Membranes
DESCRIPTION
ENERGY
NEEDED
ACTIVE or PASSIVE
TRANSPORT
Osmosis
Diffusion of water across a
selectively permeable membrane
NO
Passive Transport
Diffusion
Movement of solute from a region
of high concentration to a region of
low concentration
NO
Movement of molecules across a
membrane through protein
channels
NO
When cells take materials in by
membrane folding
YES
When cells remove large amounts
of materials
YES
TYPE
Facilitated
Diffusion
Endocytosis
Exocytosis
Passive Transport
Passive Transport
Active Transport
Active Transport
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