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Membrane Notes , Chapter 4
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Cell Membrane Structure:
A) Integral/transmembrane protein:
Doorway for molecules to enter to cell
B) Peripheral protein: Cytoskeleton
anchor
C) Phospholipid bilayer: Cell boundary,
regulates entry to cell.
Cell Membrane Structure
Cont’d
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D) Phospholipid Head: Hydrophilic Head
E) Phospholipid Tail: Hydrophobic, can be
saturated, (membrane more solid because
packed closer together) or unsaturated
(membrane more fluid because don’t pack
tightly together)
F) Cholesterol: Prevents membrane from
solidifying
Cell Membrane Structure
Cont”d
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G) Sugars: Helps as an ID tag for the
cell
H) Skip
I) Skip
J) Cytoskeleton fibers: Cell Structure
Cell membrane
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Fluid Mosaic Model
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Fluid: All the “stuff” moves around with
in the cell membrane.
Mosaic: Membrane made up of lots of
different parts.
Transport Across Membranes
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A) Passive Transport
1. Diffusion
a) particles can move either way
across the membrane, depending on
the concentration
b) size restrictions: large molecules
will not pass (WNP), charged ions WNP,
small stuff will pass!
Transport Across Membrane
Cont’d
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1) Diffusion
2) Osmosis: Diffusion
of water.
3) Facilitated
Diffusion: Some
molecules require
proteins to help them
through the membrane
(Down their
concentration gradient*
. Hi to LOW!)
*Concentration
gradient: A difference
between concentrations
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Diffusion Review
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Osmosis Review: Blue=Solute
Red=Water
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Transport Across Membrane
Cont”d
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Types of facilitated Diffusion Proteins:
1) carrier proteins*
2) Tunnel Proteins: Open tunnels that
allow passages
Are these proteins exhibiting
examples of passive
transport?
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Transport across Membrane
Cont’d
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B. Active Transport
1) Sodium Potassium Pump: In order
for neurons to work, we have to move
sodium and potassium to a particular side of
the membrane- not necessarily from an area
of high to low concentration! Pumps used to
move particles. ATP required to force
particles through.
Transporting Across
Membrane: Active Transport
cont’d
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1. Sodium Potassium Pump
2. Bulk Transport
a)Endocytosis (IN) Types:
^Pinocytosis: Cell “drinking”
^Phagocytosis: Cell “eating”
^Receptor mediated endocytosis
Specific in terms of what food
particles will
fuse with lysosomes to digest food
material.
Membrane (bulk transport
continued)
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a) Endocytosis
b) Exocytosis (OUT)
Protein carriers: ^Sodium/Potassium
Pump
^Coupled Transport
^ Proton Pump
Review of Endocytosis
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Review of Exocytosis
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