Bio1151
Chapter 7
Membrane Structure and Function
The plasma membrane is a "fluid mosaic" made of
with a mosaic of
embedded
in it, and exhibits
permeability.
Membranes are made of
which form a
bilayer
with embedded
proteins
.
Selective
allows some material to cross the plasma
membrane
.
(passive transport) is the tendency for molecules to
spread
out evenly down their
gradient.
Osmosis
determines the
of the
environment
across a membrane.
Organisms without cell
must have adaptations for
to maintain water
balance
.
Plant cells fare best in
environments
.
diffusion is the movement of molecules across the membrane facilitated by
proteins,
the concentration
gradient
.
transport
moves molecules
their concentration gradient and requires energy.
Large molecules are moved into and out of cells by bulk transport mechanisms of
and
.
In
, the cell takes in macromolecules by forming
vesicles
from the plasma membrane via invagination.
In
,
transport
migrate to the plasma membrane, fuse with it, and release their contents.
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