Transport Mechanisms (PASSIVE) Flashcards
is DIFFUSION of substance across membrane w/ no energy investment
Passive Transport
Movement of molecules from areas with HIGH concentration to LOW concentration
Does not require energy
Diffusion
In the absence of other forces, a substance will diffuse from where it is more concentrated to where it is less concentrated. (it will move down its concentration gradient)
Diffusion
No work required: spontaneous because particles have KE and are in constant motion
Diffusion
The _________ results from the unequal distribution of ions between intracellular fluid and extracellular fluid
Difference in the concentrations of the molecules in 2 areas
concentration gradient
Particles are constantly moving, as they move they colliding
Kinetic theory
Factors Affecting the Rate of Diffusion
Concentration gradient
Temperature
Mass of Particles
Solvent Properties (viscosity)
The ______ the difference in concentration, the
______ the molecules will go down the concentration gradient, hence more _____ diffusion
greater, faster, rapid
The closer the distribution of the material gets to equilibrium, the _____ the molecules will move and rate of diffusion ____.
slower, decreases
3 types in concentration gradient
Simple diffusion
Osmosis
Facilitated diffusion
No member protein involved
Can easily cross
Molecules diffuse unassisted
ex:
Benzene is non polar
Simple diffusion
Movement of molecules from HIGH concentration to LOW concentration
Both Solute and solvent mobe
Movement of solvent (water)
Water (LOW to HIGH concentration)
Solute (HIGH to LOW concentration)
Osmosis
is the movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules
Osmosis
Movement of solvent across a semipermeable membrane from high to low solvent concentration
Only solvent moves
WATER FOLLOWS SOLUTE!
Osmosis
Water uses ___ to move faster
aquaporins
Uses carrier proteins and undergo confirmation changes (context/deals w/ solute)
Facilitate diffusion
channel or carrier proteins that allow hydrophilic substances to cross membranes moving down their concentration gradients
Facilitated diffusion
a kind of protein that is found embedded in the plasma membrane of a cell
interact with the solute to be transported much more weakly
Channel protein
bind the specific solute to be transported and undergo a series of conformational changes to transfer the bound solute across the membrane
Carrier proteins
True or False
In diffusion, nonpolar molecules diffuse easily (they are soluble to the hydrophobic side)
True. Nonpolar molecules do not interact with hydrophilic heads
True or False
In diffusion, movement depends based on where the high concentration is
False. It should be in osmosis movement
_________ increase the energy and therefore the
movement of the molecules, increasing the rate of diffusion.
Higher temperatures
___________ decrease the energy of the molecules, thus decreasing the rate of diffusion.
Lower temperatures
Heavier molecules move more slowly; therefore, they
diffuse more slowly (they need greater force to change position).
The reverse is true for lighter molecules.
Mass of particles
Diffusion is significantly influenced by viscosity and density. The _______ the medium is, the harder it is for the given particle to diffuse through it. = diffusion rate would be lower
denser or viscous
If the medium is ______, then the particles will be able to move more quickly and will diffuse faster.
less dense or less viscous
Ability of a surrounding solution to cause a cel to gain or lose water
Tonicity
Depends on:
concentration of solutes that cannot cross membrane relative to the concentration of all solutes in cell
Tonicity
