The document defines key terms related to cell membrane structure, including: - The fluid mosaic model which describes biological membranes as a fluid bilayer with embedded proteins that can move laterally. - Phospholipid bilayers which are two layers of phospholipids with hydrophobic tails inward and hydrophilic heads outward. - Integral and peripheral proteins, the former embedded within the bilayer and the latter on the membrane surface. - Transport pumps and channels that use energy to move substances across the membrane against a concentration gradient.

1.
Amphipathic
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Cells & Biomolecule
molecule that has
hydrophobic and hydrophilic
regions.
Cholesterol
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Cells & Biomolecule
a lipid that prevents the
membrane from becoming
too rigid and also prevents it
from crystalizing.
Davson-Danielli
model
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model of the cell membrane
in which the phospholipid
bilayer is between two layers
of protein.

2. Fluid mosaic model
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Cells & Biomolecule
a model conceived by S.J.
Singer and Garth Nicolson in
1972 to describe the
observed structural features
of biological membranes.
Fluidity
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refers to the viscosity of a
lipid bilayer of the
membrane that allows it to
change shape.
Glycoproteins
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proteins that contain
oligosaccharide chains.

3. Hormone-binding
sites
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Cells & Biomolecule
proteins on the outside of
the membrane that allow
specific hormones to bind.
Hydrophilic
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molecules that are attracted
to water.
Hydrophobic
1.3 Membrane structure
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molecules that are not
attracted to water but are
attracted to each other.

4. Integral proteins
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proteins embedded in the
phospholipid bilayer.
Peripheral proteins
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proteins on the surface of
the plasma membrane.
Permeability
1.3 Membrane structure
Cells & Biomolecule
the rate of passive diffusion
of molecules through the
membrane, which depends
on the electric charge, size,
and polarity of the molecule.

5. Phospholipid bilayer
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Cells & Biomolecule
two layers of phospholipids
arranged so that their
hydrophobic tails are
projecting inwards while
their polar head groups are
on the outside surfaces.
Phospholipids
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a lipid consisting of a
glycerol bound to two fatty
acids and a phosphate
group.
Singer-Nicholson
model
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current model of membrane
structure that incorporates a
fluid mosaic structure in a
discontinuous lipid bilayer.

6. Transport pumps
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Cells & Biomolecule
proteins in the plasma
membrane that release
energy and use it to move
substances across the
membrane.