Chapter 6: Membrane Transport Flashcards
the diffusion of water across a selectively permeable membrane in response to concentration gradients
osmosis
- water enters by osmosis and the cell swells
- solution contains less solutes than the cell
hypotonic
- water leaves by osmosis and the cell shrinks
- solution contains more solutes than the cell
hypertonic
the concentrations of solutes than the cell inside and outside the cell are balanced
isotonic
- strong walls prevent plant cells from bursting
- pushes cells tightly against their walls and supports soft tissues
turgor pressure
plant cells shrink so much that they retract from their walls
plasmolysis
- transport of substances across a membrane against a concentration gradient requires this
- a process that requires energy input
active transport
active transport of ions contributes to an electrical potential difference across the plasma membrane
membrane potential
the protein that transports a substance also hydrolyzes ATP to power the transport directly
primary active transport
transport is indirectly driven by ATP hydrolysis
secondary active transport
generate membrane potential, and regulate pH in lysosomes and vacuoles
H+ pumps
moves Ca2+ from the cytoplasm to the cell exterior, and from the cytosol into the vesicle of the endoplasmic reticulum
Ca2+ pump
the plasma membrane of all animal cells moves 3 Na+ out of the cell and 2 K+ into the cell in the same pumping cycle
Na+/K+ pump
- the differences in concentration of ions and in electrical charge on the two sides of the membrane
- a form of potential energy
electrochemical gradient
the solutes moves through the membrane channel in the same direction as the driving ion
symport
