PLASMA MEMBRANE GUIDED NOTES
Name: ________________________________
PLASMA MEMBRANE
Selectively permeable barrier between the cell and the environment.
What does ‘selectively permeable’ mean?
_________________________________________________________________________________________________
__________________________________________________________________________________________________
Selective permeability is necessary for the cell to maintain the correct internal
environment for physiological functions.
PLASMA MEMBRANE STRUCTURE
 Phospholipids
◦ Make up the majority of the membrane
◦ Arranged in a bilayer, with hydrophilic heads outside, and hydrophobic tails inside
Hydrophilic = ______________________
Hydrophilic molecules are __________________ like water.
Hydrophobic = _____________________
Hydrophobic molecules are _________________ like oil.
____________________________ can interact with watery external environment and watery
cytoplasm.
____________________________ reduce the diffusion of water and other charged or polar
substances across the membrane.
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 Cholesterol
◦ Makes the cell membrane more ______________ and less
_________________________________________________
 Proteins
◦ Act as _________________________________________________________________
_______________________________________________________________________
 Glycoproteins and Glycolipids
◦ Glyco = ___________________________
◦ Influence cell interactions (e.g. identifying cell as ‘self’) and molecule transport
CELL MEMBRANE TRANSPORT VOCABULARY
 __________________ a dissolving agent (water, usually)
 __________________ substances dissolved in a solution
 __________________ watery environment outside cells
 __________________ lower solute concentration
 ________________ higher solute concentration
 ________________ equal solute concentration
TRANSPORT MECHANISMS
Transport of materials across the cell membrane can be characterized as passive or active.
Passive mechanisms require __________________________ from the cell. ALL passive
mechanisms transport molecules ____________________________________________.
Active mechanisms require _________________ from the cell.
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PASSIVE TRANSPORT
Diffusion is the _________________________________________________________________
_____________________________________________________________________________.
Results from the random movement of molecules.
 Simple Diffusion ______________________________________________________________________
______________________________________________________________________.
Only works for tiny OR non-polar molecules.
Examples: fats, fat-soluble vitamins, O2, CO2, Cl Osmosis is ________________________________________________________.
 Facilitated diffusion - __________________________________________________; used for large
polar molecules
◦ Example: glucose
 Filtration occurs when water and solutes are pushed __________________________
_____________________________________________________________________.
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Water and solutes move down pressure gradient.
Process by which blood is filtered in the kidney.
ACTIVE TRANSPORT
Active transport requires _________________________________to transport material across the cell.
Active transport is used for
◦ Solutes moving ________________________the concentration gradient
- or ◦ Very_______________ substances
 Solute Pumping (aka active transport)
Membrane proteins (called solute pumps) ______________________to carry solutes
_______________________their concentration gradient.
Examples: amino acids and most ions
 Exocytosis - movement of materials _________________________ by vesicle
Examples: hormones, neurotransmitters, mucus, some wastes
 Endocytosis – movement of materials ______________________ by vesicle
o Phagocytosis (cell eating) – white blood cells engulf bacteria, dead cells, and
foreign debris
o Pinocytosis (cell drinking) - used to take up droplets of fats and dissolved proteins
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