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Membrane Notes: Ch. 4
KEY WORDS/
QUESTIONS
Cell Membrane
Structure
Fluid Mosaic
Model
NOTES
A: Integral/transmembrane protein: doorway for
molecules to enter cell
B: Peripheral protein: cytoskeleton anchor
C: Phospholipid bilayer: cell boundary,
regulates entry to cell
D: Phospholipid head: hydrophilic
E: Phospholipid tails: hydrophobic, can be
saturated (membrane more solid b/c pack closer
together) or unsaturated (membrane more fluid b/c
don’t pack tightly)
F: cholesterol: prevents membrane from
solidifying
G: sugars: helps as an ID tag for the cell
H: skip
I: skip
J: cytoskeleton fibers: cell structure
Fluid: all the stuff moves around with in the
cell membrane
Mosaic: membrane made up of lots of different
parts
Membrane Notes: Ch. 4
Transport Across
Membranes
A. Passive Transport
1.
Diffusion:
a. particles can move either way across the
membrane, just depends on concentration
b. size restrictions:
i. large will not pass (WNP)
ii.
charged ions WNP
iii. small will
2.
Osmosis:
diffusion of water
3. Facilitated Diffusion: some molecules require
proteins to help transport through the membrane (down their
concentration
gradient)
*Types of Facilitated Diffusion Proteins
1. Carrier Proteins: show book animation with carrier
proteins
2. Tunnel Proteins: just open tunnels that allow passage
B. Active Tranport
1. Sodium Potassium
Pump: image below
keys on the fact
that for neurons to
work (mostly where
you would find these
pumps) we have to
move sodium and
potassium to a
particular side of
the membrane – not
necessarily in
conjunction with how particles would normally go based
on concentration. So, use pumps to get them to the
correct side. ATP required to force them through.
2. Bulk Tranport:
a. Endocytosis
Types:
i. Pinocytosis: Cell
drinking (General)
ii. Phagocytosis: Cell
eating large particles
(general)
Receptor Mediated
iii. Endocytosis: More
specific in terms of what
is being brought in
Membrane Notes: Ch. 4
*Food particles will fuse with lysosomes to digest
food material. Food that is needed will difuse out
of the particle, the rest/waste will be released
via exocytosis
b. Exocytosis