diffusion - mov't of molecules from higher to lower concentration
- continues until concentration is uniform
- allows certain polar molecules to enter through the channels
- inner, polar lining of channels allow polar molecules to enter
- each channel is selectively permeable, only allowing certain molecules to pass through
- ions need transport proteins to move in/out of the cell
- ion channels - have hydrated interiors so that ions never come in contact w/ nonpolar fatty acids
- voltage and concentration determine direction of ions
- carriers - brings substances across the membrane by binding to them at 1 end and releasing them out the other
- depends on the concentration gradient of the substance being transported
- performs facilitated diffusion (either specific, passive, or saturated)
- certain red blood cell proteins transfers different molecules in different directions
- glucose transporter - adds phosphate group to glucose to keep internal glucose levels low; used by red blood cells to attract more glucose molecules
- saturation - occurs when all the protein carriers are used up; transport rate can no longer increase
osmosis - both water/solutes move from higher to lower concentrations
- aquaporins - specialized channels for water
- water moves towards area of more concentrated solutes to form hydration shells
- osmotic concentration - concentration of all solutes in a solution
- hyperosmotic - solution w/ higher concentration
- hypoosmotic - solution w/ lower concentration
- isosmotic - solutions w/ equal concentrations
- water flows towards hyperosmotic region
- hydrostatic pressure - pressure of cytoplasm pushing out against the cell membrane; tends to drive water out of the cell
- osmotic pressure - pressure needed to stop the mov't of water across the membrane; tends to drive water into a cell
maintaining equilibrium - important to have balance between pressures
- animals need to keep isosmotic conditions more than plants/fungi due to lack of cell walls
- extrusion - used by single-celled eukaryotes w/ vacuoles
- vacuole collects water from the cell, pumps it out by contracting rhythmically
- isosmotic solutions - some animals use their environment to adjust internal solute concentration
- ocean organisms' internal conditions match that of seawater
- blood contains protein albumin to raise solute concentration of liquid blood to match that of the cells
- turgor pressure - internal hydrostatic pressure
- makes plants rigid by pressing against the membrane/cell wall
- maintains shape of plants
Subject:
Subject X2:
