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50 terms

Combo with Osmosis, Diffusion, Tonicity, and Cell Permeability and 1 other

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Diffusion
random movement of molecules down a concentration gradient from area of high solute concentration to and area of low solute concentration
Factors Affecting Rate of Diffusion
1. Molecular Weight- larger molecular weight solutes will not cross semi-permeable membrane.
2. Temperature- high temp increases kinetic energy thus increasing rate of diffusion
3. Polarity- polar substances diffuse inw ater more easily
4. Permeability of membrane- ioniztion properties of different solutions retard rate of diffusion
5. Concentration of substance- more concentration equals more diffusion
Osmosis
type of diffusion involving movement of H2O across semi-permeable membrane
-SPM prevents solute particles from crossing but allows solvent molecules (H2O) to move freely
-solvent moves from high to low solvent concentration
Osmotic Pressure
hydrostatic back pressure required to cancel osmotic diffusion of H2O from one side of osmometer to the other
Calculation of Osmotic Pressure
pi = iRT (C1-C2)

pi - osmotic pressure
i= total # of ions dissociated from each molecule in solution
R- gas constant
T= temp (K)
M= molarity= C1 and C2
C1= concentration gradient of sucrose in bag (moles/L)
C2= concentration gradient of sucrose in beaker (moles/L)

See Quiz
Osmole
# of particles in solution expessed as osmoles/ L
Osmolarity
osmolarity= (molarity)(# of ions)
Isoosmotic
inside and outside cell is the same
hyperosmotic
outside the cell has greater pressure than inside the cell
hypoosmotic
outside the cell has less pressure than inside the cell
Tonicity
ability of extracellular solution to cause a change in the shape or size of cell
*always named in respect to extracellular environment
Cell Isotonicity
extracellular and intracellular are the same
Cell in hypertonic solution
-solvent rushes out of the cell
-cell shrivels (crenates)

animal cell crenation = plant cell plasmolysis
Cell in hypotonic solution
-solvent rushes into the cell
-cell bursts (lysis)

hemolysis-> bursting of red blood cell
Tonicity and Erythrocytes (red blood cells)
cells in distilled water- swell and burst
cells in concentrated salt solution- shrivel
Tonicity and Plant Cells
cells in distilled water- stiffen but retain shape
cells in concentrated salt solution- cell body shrinks and pulls away form cell wall
Edema
disruption of homeostasis
cells in body swill with increased consumption of salt
disease condition
pregnancy
varies from bloating to pitting
equilibrium
when the concentration is the same throughout the substance
passive transport
when molecules don't use any energy to diffuse
how do small uncharged molecules pass through membrane
they go through and dissolve
how do large molecules go through
quickly and carried across by protein channels
facilitated diffusion
when the channels help dissolve the large molecules that pass through the membrane
water molecules need facilitated diffusion because
the lipid bilayer is hydrophobic
aquaporins
water channel proteins
isotonic
when the sugar and water concentrations on either side of the barrier are equal
hypertonic
when the water molecules are more numerous or stronger outside of cell so they all rush into cell causing it to swell
hypotonic
when the concentration is weaker within the cell so all the molecules rush out causing it to deflate
osmotic pressure
the different movements of water molecules in and out of the cells
Active transfer
energy-requiring movement of materials against diffusion
3 effects of osmosis on an animal cell
isotonic, hypertonic, hypotonic
turgor pressure
pressure of central vacuole on cell wall
how does osmotic pressure affect plant cells
causes size change of central vacuole
diffusable molecules
small molecules, uncharged ions, gasses, lipids
facilitate diffusable molecules
polar molecules and ions
cytolysis
if too much water moves in too an animal cell and it bursts
plasmolysis
Occurs in walled cells; the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment.
water potential
the combined effect of solute concentration and pressure. The formula is pressure plus osmotic potential (which is always negative). Measures the tendency of water to leave one cell compartment for another
crenation
cell shRinks when the solution is hypeRtonic
water potential of pure water
0
the water potential of any solution at atmospheric level
negative (bc osmotic pressure is negative)
flaccid
Limp; lacking firmness, as in plant cell surroundings where there is no tendency for water to enter the cell.
turgor pressure
an increase in the internal pressure of a cell as water flows into it.
concentration gradien
the driving force of the net flow of molecules in or out of a cell, no energy is needed to drve the flow since all the movement is due to the greater concentration of molecules on one side than the other.
tonicity
is the ability of a solution to cause a cell to gain or lose water
Is the permeability of the membrane to solutes important for osmosis? Explain.
...
Order in which water moves in plants
the soil -> roots -> leaves (water potential from high to low-negative)
In your experiment, as solute is added to the water in the beaker, what happens to the potato cells?
When a solute is added, the water potential of the solution becomes negative. This means that water must flow from the higher water potential inside the potato cell to the lower water potential outside the potato cell until the two are equal. In this experiment's terms, this means that the potatoes would lose weight to water.
Why does a low concentration of solute result in a high water potential
water molecules have a lot of potential energy because they are free to move around and not bound to solute
How does water travel to the leaves from the roots?
As transpiration happens, this leads to the formerly higher water potential in the leaves to becomes water potential that is lower than that at the roots. This causes the water to want to move from high to low water potential. The way it beats gravity is by cohesion and adhesion.
transpiration
Loss of water vapor by diffusion and evaporation . Occurs because air inside a leaf has a higher water potential than air outside the leaf, thus leading to water movement out of the leaf.