Membranes - transport, osmosis Flashcards
What are the components/characteristics of the phospholipid bilayer?
2 phospholipid molecules (hydrophobic tails inward, hydrophilic head outwards)
- amphipathic
unsaturated or saturated tails (affect fluidity)
proteins
how does unsaturated/saturated tails, and cholesterol affect the membrane fluidity?
unsat. - above a certain phase transition temp. membrane is more fluid
sat. - below a certain phase transition temp., membrane is more solid
choles. - aids in maintaining the fluidity of the membrane (not too fluid, not too solid)
What does isotonic, hypertonic, hypotonic solutions?
isotonic - solute concentration = solution concentration
hypertonic - solute concentration in cell is less then solute concentration outside the cell
hypotonic - solute concentration in cell is greater then the solute concentration outside the cell
What if you put an animal cell in a hypotonic/isotonic/hypertonic solutions?
hypotonic - cell gains water (lysed)
isotonic - normal (equal amount of water)
hypertonic - cell loses water (shriveled)
What if you put a plant cell in a hypotonic/isotonic/hypertonic solutions?
hypotonic - cell gains water (turgid, normal)
isotonic - flaccid (equal amount of water)
hypertonic - cell loses water (plasmolyzed)
What is osmosis?
diffusion of free water across a selectively permeable membrane
How does water move?
low concentration of solute to high concentration of solute
what type of transport is osmosis?
passive transport
what is the difference of osmosis and diffusion?
osmosis - movement of water
diffusion - movement of molecules
what is facilitated diffusion?
passive transport aided by proteins
- hydrophilic substances (polar and charged)
Explain active transport using H+ pumps.
process where cells move protons against their concentration (low to high) using energy
Explain in your own words - cotransport
process in which the movement of one substance across a cell membrane is coupled with the movement of another substance (Na/K pump)
Explain the processes of exocytosis and endocytosis.
exo - process where cells expel substances from the cell interior to the environment; fusion of vesicles to membrane
endo. - process where cells take in substances from the external environment by engulfing them; formation of vesicles from the cell membrane to enclose these materials
what are the 3 types of endocytosis?
phagocytosis, pinocytosis, receptor-mediated endocytosis
what is phagocytosis?
process of engulfing large particles, macrophages use this to eliminate foreign invaders
