PASSIVE TRANSPORT Flashcards
Cell Transport
Active and Passive
Active Transport
Use of energy
- molecular (ion pumps)
- Endocytosis/Exocytosis
Passive Transport
Doesn’t require energy
- Diffusion
- Osmosis
- Facilitated Diffusion
Diffusion
Particles moving from greater conc. to lower conc. until equilibrium is reached.
- conc. gradient
- solid, liquid, and gas
- Passive
- REVERSIBLE
Simultaneous diffusion
exchange O2 for CO2, diffusing 2 substances at the same time
Dynamic equilibrium
when particles continue to move but overall conc doesn’t change, moving molecules but no conc. difference
Facilitated Diffusion
- particles move through protein channels
- polar molecules and ions cannot go directly through the membrane (Glucose, Sodium ions, Chloride ions)
- Fast and Specific
- ONLY occurs if high conc. on one side of the cell
- Goes both in and out of the cell depending on conc.
Transport Protein
only if crossed by bilayer, “transmembrane proteins”
- Each molecule has its own protein channel
- Due to the amino acid side “R” chain
- can be neutral, positive, or negative
2 types of transmembrane proteins
- Carrier proteins
- Channel proteins
Carrier Proteins
- Transported molecules bond themselves to the protein, making it open
- can be uni and bi directional
Channel Proteins
- Acts like a pore
- Allows water and small ions through the membrane quickly
- both entry and exit
Osmosis
Diffusion of water
Osmotic pressure
pressure on the hypertonic side of a selectively permeable membrane
Aquaporins
Special water movement channels that allow large amounts of water to move along conc. gradient
Hypertonic
more solute
