Cell Membranes And Transport Flashcards
Definition of diffusion
The passive movement of a molecule or ion down a concentration gradient until equilibrium is reached.
Definition of facilitated diffusion
The passive transfer of molecules or ions down a concentration gradient across a membrane by carrier protein molecules in the membrane
Definition of active transport
The movement of molecules or ions across a membrane against the concentration gradient, using energy from the hydrolysis of ATP made by the cell in respiration.
Definition of osmosis
The diffusion of water, from a region of higher water potential to a region of lower water potential, through a selectively permeable membrane.
Definition of solute potential
A measure of the osmotic strength of a solution.
Definition of pressure potential
The pressure exerted by the cell contents on the cell wall.
Definition of water potential
A measure of the free energy of water molecules (kPa)
Definition of turgid
A plant cell that holds as much water as possible. Further entry of water is prevented as the cell wall cannot expand any further
Definition of plasmolysis
Plant cells in hypertonic solution loose water by osmosis. The vacuole shrinks and the cytoplasm draws away from the cell
Definition of flaccid
Floppy
Plasmolysis is complete
Cannot provide support- plant wilts
Definition of haemolysis
Red blood cells in distilled water- water enters the cell and they burst.
Definition of hypotonic
Water potential of external solution is higher than solution inside the cell
Water flows into cell
Turgid
Definition of hypertonic
Water potential of external solution is lower than solution inside cell
Water leaves the cell
Plasmolysis
Definition of isotonic
Cell had the same water potential as surrounding solution
No net water movement
Why is it called the fluid mosaic model?
Phospholipid molecules can move
Proteins vary
