Download Cell Membrane Notes

Cell Membrane Notes
Slide one: cell membrane vs. cell wall
 Cell Membranes _________________ what comes into and out of cells
 Cell Walls provide _____________________________________ for the cell
Slide two: Phospholipids make up cell membranes
Drawing of phospholipid:
Slide three:
 Sketch a diagram of how phospholipids might group together if they are mixed with water.
Remember the “rules”:
1. The “heads” face towards water
2. The “tails” face away from water and are attracted towards tails of other phospholipids
How many different arrangements will work?
Slide four: Draw lipid bilayer
Slide Five: Membranes are picky!!!
 Membranes are ______________________ because they only let certain molecules through
 ______________________________________ can pass through easily (water, oxygen, carbon
dioxide)
 _____________________________________________ cannot pass through without help
(starch, glucose, proteins, amino acids, ions)
Slide six: Diffusion and Osmosis
Diffusion- The _______________________________________ from a region of
_________________________ to a region of _______________________________, caused by the random
motion of particles.
Osmosis- The _____________________________________ across a semi-permeable membrane towards the
side with higher solute concentration.
Slide seven: Why does osmosis happen?
Two factors cause osmosis:
1. A semipermeable membrane allows water molecules to move back and forth through the membrane, but
not solute molecules
2. Water molecules “stick” temporarily to any dissolved solute molecules.
As a result, water molecules spend more time and accumulate on the side of the membrane with the higher
concentration of dissolved solutes.
Slide eight: Solutions
 Solute- ___________________________________________________________
 Solvent- ____________________________________________________________
 Example
In a solution of salt dissolved in water:
Salt is the solute; water is the solvent
Slide nine: Types of solutions
 hypertonic solution hypotonic solution isotonic solution
Slide ten: Facilitated diffusion
The movement of molecules across a cell membrane from an area of higher concentration to an area of lower
concentration with the help of a carrier protein. This transport does ____________________________ to
happen.
Slide eleven: Active transport
The movement of molecules across a cell membrane from an area of
___________________________________________________________________ (“up” or “against” the
concentration gradient). Active transport ___________________________________________
Slide twelve: Passive transport
Passive transport happens spontaneously across the cell membrane. It does
________________________________________ (ATP) because molecules move DOWN their concentration
gradients (from high to low concentration).
There are two types of passive diffusion:
1. Simple diffusion:
2. Facilitated diffusion:
Slide thirteen: 3 steps in facilitated diffusion
1. Particle binds to one side of _______________________________
2. __________________________________ changes shape
3. Particle ______________________________to other side of membrane