Download Biology 12 Membrane Notes (Blanks) File

Biology 12 – Membrane Notes
Fluid-Mosaic Model
•
Cell membranes are sometime described as a fluid mosaic
! Why Mosaic?... the ______________ and __________________ in/on the
phospholipid bilayer form a pattern (mosaic) within the bilayer
! Why Fluid?... the proteins and carbohydrate chains in/on the phospholipid bilayer
can _________ around in the bilayer (fluid)
Selectively Permeable
•
Cell membranes are selectively permeable (not just semi-permeable)
! What’s the difference?
o Semi-permeable = a membrane (e.g. dialysis tubing) that materials can pass
through simply based on ____________ and
_____________________________
o Selectively permeable = a living membrane that can use ___________to select
molecules (even if they are too big or the concentration gradient is going in the
opposite direction)
Six Ways In/Out of Cells
•
Molecules enter/leave cells based on size, shape of molecule, charge of the molecule,
concentration gradient, and cell “need”
" some molecules can pass right through the bilayer (①_______________and
②______________)
" some molecules travel through protein channels/carriers
(③_________________________ and ④__________________)
" some molecules enter/leave using vesicles or vacuoles (⑤_______________ and
⑥_________________)
① Diffusion
•
natural physical process where molecules move from an area of high concentration
to an area of low concentration
o _________________ process (doesn’t need extra energy)
o occurs within cells (cytoplasm), outside cells (extracellular fluid) and through
the bilayer (*molecules must be small and neutral eg. O2, CO2, alcohol)
o rate of diffusion affected by:
#
temperature
#
size of the molecule
#
concentration gradient
#
fluid viscosity
#
fluid currents
② Osmosis
= the diffusion of water across a semi-permeable (or selectively permeable) membrane
o water moves from an area of high [water] ! low [water] OR water will move to
____________ a ___________
• Important Definitions
o ____________________ = the force that results from the osmotic flow of water
#
can “pop” an animal cell or keep a plant cell turgid
o __________________ = the amount of solute in a solution (in mol/L or %)
#
_____________ = equal solute concentration
#
_____________ = greater solute concentration
•
Animal cells (e.g. Red blood cells) placed in a hypertonic solution
will lose water and shrink/shrivel (“crenation” for RBCs)
•
#
Plant cells in a hypertonic solution will wilt (“plasmolysis”)
_____________ = lower solute concentration
•
Animal cells placed in a hypotonic solution will gain water and burst
(“lysis” or “hemolysis” in RBCs)
•
Plant cells in a hypotonic solution will get tight (“deplasmolysis” or
“turgor”)