The cell is highly organized with many functional units or organelles. Most of these units are limited by one or more membranes. To perform the function of the organelle, the membrane is specialized in that it contains specific proteins and lipid components that enable it to perform its unique roles for that cell or organelle. In essence membranes are essential for the integrity and function of the cell.
Membrane components may:
be protective
regulate transport in and out of cell or subcellular domain
allow selective receptivity and signal transduction by providing
transmembrane receptors that bind signaling
molecules
allow cell recognition
provide anchoring sites for cytoskeletal
filaments or components of the extracellular matrix. This allows the cell to maintain
its shape and perhaps move to distant sites.
help compartmentalize subcellular domains or microdomains
provide a stable site for the binding and catalysis of enzymes.
regulate the fusion of the membrane with other membranes in the
cell via specialized junctions )
provide a passageway across the membrane for certain molecules,
such as in gap junctions.
allow directed cell or organelle motility
Which component (s)
of membranes give it its fluid characteristics?
What feature in a membrane helps to prevent freezing? Be specific.
Which part of a membrane helps it keep its shape (prevents deformation)?
How are proteins
arranged in a membrane? What is the difference between a transmembrane protein and a
peripheral membrane protein?
What is a microdomain,
and how is it formed?
If one type of membrane contains 76% proteins and another type
contains only 18% proteins, what might you conclude about functional differences? For
example, see Membrane Architecture
What experiments might you
conduct to prove that proteins moved in the plane of the membrane?
How do membranes support the polarity of a cell?
How would you detect receptors
in the plasma membrane of a cell?
In a freeze-fracture/freeze
etch specimen, what are the bumps seen in the plane of the membrane?
How would you distinguish tight,
or occluding junction between two cells, both structurally and functionally.
What experiments would you use to prove cells were communicating
via gap junctions? Do you know how gap junctions are formed?
What does the presence of microvilli
signify?
What experimental approach could you use to show that a protein is inserted in the membrane?
