I. The Cell Membrane
Function:
1. Plasma membrane is _extremely pliable____, allowing for certain
molecules to enter the cells while others cannot.
Cell membrane characteristics:
2. Phobicity
a) Hydrophobic repels and is repelled by water
b) Hydrophilic attracted to water
c) Amphipathic has both hydrophilic and hydrophilic regions
(1) Membrane lipid
3. Fluids
a) Intracellular fluid (ICF) is found in the ___interior of cell________
b) Interstitial fluid (IF) is found in the ___extracellular build not in
blood vessels __________
c) Extracellular fluid (ECF) is found in the ___outside the cell______
4. Membrane proteins
a) Integral proteins: protein embedded In the membrane
(1) Channel: an integral protein that selectively allows
particular materials
, (2) Recognition proteins serve to mark a cells identity so it can
be recognized by other cells
(a) Receptor: recognition protein that selectively bind a
specific molecule outside the cell, binding induces a
chemical reaction
(i) Ligand: specific molecule that binds to and
activates a receptor
(3) Glycoproteins: protein that has carbohydrate molecules
(a) Glycocalyx: fuzzy appearing coating around the
cell formed nay glycoproteins and other
carbohydrates attached to the cell membrane
b) Peripheral proteins: typically found on the inner or outer surface if
the lipid bilayer. Typically perform a specific function for the cell
5. Membrane transport
a) Passive transport: movement of substances across the
membrane without expenditure of cellular energy
(1) Simple diffusion: allows small uncharged substances to
pass through cell membrane. Oxygen, CO2 and
hydrophobic molecules
(a) How is spraying Lysol in one corner of your room
an example of simple diffusion? The molecules
would leave the bottle and diffuse from the bottle to
to all parts of the room until nor more concentration
gradients remain
(2) Osmosis: diffusion of water through a semipermeable
membrane
(a) How is osmosis different from simple diffusion?
Osmosis occurs when there is an imbalance
solutes outside of the cell versus inside