Membrane Dynamics

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Membrane Dynamics
Cell Structure and Function - Chapter 5

• Using Xs draw a blood cell in a hypertonic
  environment.
• Which way is the water going to move?
• Why?
• Label ECF and ICF

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Which cell is in a hypertonic environment?
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Membrane Dynamics
Cell Structure and Function - Chapter 5

• Review Key Terms
• Osmosis
• Diffusion
• ICF/ ECF
• Hypertonic/ Hypotonic/ Isotonic
• Be able to predict what will happen to water!

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Diffusion across a membranePassive TransportNo
energy reqddown concentration gradient
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Passive Transport Facilitated Diffusion
The passive movement of molecules down its
concentration gradient via a transport protein is
called facilitated diffusion Aquaporins
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Facilitated Diffusion Gated Ion Channels
Some transport proteins do not provide channels
but appear to actually translocate the
solute-binding site and solute across the
membrane as the protein changes shape.
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Active TransportRequires E (ATP)Against the
concentration gradientUPHILL!
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Using The Gradients Energy
HIGH concentration of H ions
Chemiosmosis The movement of H ions down its
concentration gradient is harnessed to the
synthesis of ATP. What organelle? How can you
concentrate the H ions? What protein is shown?
LOW concentration of H ions
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Through the Membrane
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Transport with the Membrane E reqd
In phagocytosis, the cell engulfs a particle by
extending pseudopodia around it and packaging it
in a large vacuole.
In pinocytosis, cellular drinking, a cell
creates a vesicle around a droplet of
extracellular fluid
Receptor-mediated endocytosis is very specific in
what substances are being transported. This
process is triggered when extracellular
substances bind to special receptors, ligands, on
the membrane surface, especially near coated
pits. This triggers the formation of a vesicle