Chaper 5 - Membrane Structure and Function Flashcards
When net movement stops ?
Equilibrium
When the net movement of molecules down a concentration gradient?
Diffusion
When soluble molecules pass through the membrane by diffusion this is …
Lipid
Focuses on solvent (water) movement rather than solute. Also a special case of diffusion.
Osmosis
Diffusion of water across a __________- permeable membrane.
Selectively
The pressure that develops in cells die to osmosis.
Osmotic Pressure
A plant wilts because of two reasons:
Loss or water and loss of turgor pressure
Solute and water concentrations both inside and outside the membrane are equal and no net gain or loss of water by the cell.
Isotonic solution .
Concentration of solute in the solution is lower than inside the cell so swells because water moves on also Lyse (cytolysis)
HypOtonic Solution
Concentration of solute is higher in the solution than inside the cell , plasmolysis and crenation.
Hypertonic Solution
These molecules must combine with the carrier proteins to move across the membrane
Facilitated transport
Requires the expenditure of energy in the form of chemical ATP.
Ex: sodium-potassium pump
Active Transport
Vesicles fuse with plasma membrane and secrete cell contents/products from the cell.
Exoxytosis
Cells engulf substances into a pouch which becomes a vesicles, and then brings the vesicles into the cell.
Endocytosis
Large, solid material into vesicle.
-“cell eating” like an amoeba.
Phagocytosis
Vesicles form around a liquid or very small particles.
-“cell drinking”
Pinocytosis.
Specific form of pinocytosis using receptor proteins and a coated pit.
Receptor-mediated
Intercellular filaments between cells
Adhesion junctions
Internal cytoplasmic “spot welds.”
Desmosomes
“Zipper-like” ring that forms impermeable barriers
Tight Junctions
Plasma membrane channels are joined ( allows communication occur between cells)
Gap Junctions
Plants have a freely permeable _______ with cellulose as the main component.
Cell wall
_________________ penetrate the cell wall.
- allows passage of material between cells.
Plasmodesmata
