Chapter 2- Membrane Diffusion Flashcards
Simple Diffusion
-Flow of small, uncharged non-polar substances
(O2 and CO2) across cell membrane down the concentration gradient (high to low) WITHOUT using energy
Osmosis
-simple diffusion that involves water molecules (water is polar, but small enough to cross membrane)
Facilitated transport
- integral proteins allow large hydrophilic molecules to cross cell membrane.
- these proteins are: uniporters, symporters, antiporters
Uniporters
-facilitated transport of single substance in one direction
Symporters
-facilitated transport of two substances in the same direction
Antiporters
-facilitated transport of two substances in the opposite direction
Channel proteins
-open tunnels that face both sides of bilayer.
Carrier Proteins
-binds to molecule on one side and changes shape to transport to the other side
Passive diffusion
- type of facilitated transport that is done by channel proteins
- bringing molecules down their concentration gradient without energy use.
- Similar to simple diffusion but a channel protein is used.
- Ex: porins for hydrophilic molecules and ion channels for ions.
Active Transport
-substances travel against their concentration gradient and require the consumption of energy by carrier proteins.
Primary Active transport
- uses ATP hydrolysis to pump molecules against their gradient.
- Ex: Sodium-potassium (Na+/K+) pump
Secondary active transport
-uses FREE energy released when other molecules flow down their concentration gradient to pump the desired molecule across the membrane.
Cytosis
-the bulk transport of large, hydrophilic molecules across the cell membrane and requires energy.
Endocytosis
- cell membrane engulfing an extracellular substance internalizing it
- via vesicle or vacuole
Phagocytosis
-cellular EATING around solid objects
