CELL TRANSPORT
Homeostasis
Membrane permeability
Equilibrium
Transport
Homeostasis: Maintaining a Balance
____________________________________________________________________
What Maintains Homeostasis?
The PLASMA MEMBRANE maintains the proper concentrations of materials by controlling
the passage.
Characteristics of the Cell Membrane
Selectively Permeable aka _________________________
1. Water, oxygen, nitrogen, carbon dioxide and other small nonpolar molecules can
diffuse directly
2. _______________________________________________________________
Plasma Membrane-Structure
1. Phospholipid Bilayer2. 2 fatty acids and 1 phosphate group attached to a glycerol
3. Polar Heads (water soluble)
4. Non Polar -Fatty acid chain (not water soluble)
____________________________________________________________________
____________________________________________________________________
Plasma Membrane Function-Proteins
• The cell membrane's function in general, revolves around membrane proteins.
Receptor proteins: _____________________________________________________
2. Transport or channel proteins: __________________________________________
3. Marker proteins:_____________________________________________________
Cellular Transport
NO ENERGY REQUIRED
•
•
•
ENERGY REQUIRED
• Active Transport
Diffusion  Passive Transport-________________________________________________
• Concentration gradient - ____________________________________________
• When the molecules are even throughout a space - it is called ________________
A. Osmosis - the diffusion of water molecules through a selectively
permeablemembrane. (_________________)
Ex.Water will move in the direction where there is a high concentration of solute (and hence
a lower concentration of water).
Isotonic Solution
• _____________________________________________________________
• _____________________________________________________________
Hypotonic Solution
 There are less solute (salt) molecules in the solution.
 _____________________________________________________________
 Cell will swell
 Cell could burst
 _____________________________________________________________
Hypertonic Solution
A. There are more solute (salt) molecules in solution, which causes the water to leave
the cell
B. Plants wilt and animal cell shrink-______________. In both cases, the cell may die.
Describe how red blood cells look in each situation.
a. isotonic
b. hypotonic
c. hypertonic
Facilitated Diffusion
(_______________________________________)
• Moves substances down the concentration gradient without using cell’s energy
• Use of carrier proteins located in membrane
Active Transport
Move particles from a region of lesser concentration to a region of greater concentration.
Move against the concentration gradient. Must use energy (_______)
Endocytosis and Exocytosis
Cells can also move things in and out by using pieces of membrane.
Endocytosis:
pinocytosis – cellular _______________ phagocytosis – cellular _________________
Exocytosis:
-
can involve getting rid of waste, or can involve secreting cell products (such
as hormones or other important compounds)
___________________________________________________
Exocytosis- substances inside a vesicle are released from a cell as the vesicle fuses with
the cell membrane
• __________________________________