(1/4) BR Osmosis review: if a selectively permeable membraneseparates a hypertonic solution from a hypotonic solution,in which direction will WATER flow? Animal cell Plant cell (3) Shriveled (crenation)
Isotonic solution Hypotonic solution Hypertonic solution H2O H2O H2O H2O Animal cell (1) Normal (2) Lysed (hemolysis) (3) Shriveled (crenation) Plasma membrane H2O H2O H2O H2O Plant cell (4) Flaccid (5) Turgid (6) Shriveled (plasmolysis) Osmosis: water moves from a hypotonic solution into a hypertonic solution
Cells take in water and may burst (hemolysis) Cells lose water and shrivel (crenation) Cells stiffen and become turgid Cell body shrinks away from cell wall (wilting) If pressure builds or is applied on the hypertonicside, it can counteract the movement of water intothe solution Water Potential: = s + p
Osmosis: Water moves from area of high water potential(hypotonic solution) to low water potential (hypertonic) s = solute potential p = pressure potential (= 0 at atmospheric pressure) s =-iCRT i ionization constant C molar concentration (mol/L of solute in water) R pressure constant( L-bars/mol-K) T temperature in Kelvin (0C + 273) At equilibrium both sides of the membrane have equal Plasma membranes typically are impermeable to solutes Animal cells have no significant p Plant cells have significant p in hypotonic solutionswhat isthis internal pressure called? When water leaves a cell, concentration (C) increases so its sbecomes more negative Water Potential Water molecules surround solutes, decreasing waters free energy AND water potential Hypertonic solutions have LOW water potential Water Potential practice = s + p
The initial molar concentration of the cytoplasm inside aplant cell is 1.3M and the surrounding solution is .3M. Is it possible for the cell to be in equilibrium? Explain. If the cell is initially flaccid, in which direction will watermove by osmosis? A cell is in equilibrium with its environment.The solutepotential (s) of the cells cytoplasm is 0.45 bars.Thewater potential of the surrounding solution is 0.32 bars. When the cell was first put into the solution, it was flaccid. In which direction did water move by osmosis? What is the pressure potential (p) of the cell? Is the cell hypertonic, hypotonic, or isotonic to itssurroundings? Water Potential practice = s + p
The initial molar concentration of the cytoplasm inside aplant cell is 1.3M and the surrounding solution is .3M. Yes because of turgor pressure in cell Into the cell A cell is in equilibrium with its environment.The solutepotential (s) of the cells cytoplasm is 0.45 bars.Thewater potential of the surrounding solution is 0.32 bars. When the cell was first put into the solution, it was flaccid. .13 bars hypertonic Water Potential practice = s + p
A cell is in equilibrium with its surroundings.The molarityof the surrounding solution is 0.5M, and the temperature is200C. Calculate the solute potential (s) of the solution. What is the water potential of the solution? What is the water potential of the cell? Why cant we calculate the solute potential of the cell? s =-iCRT i ionization constant (assume i = 1) C molar concentration (mol/L) R pressure constant( L-bars/mol-K) T temperature in Kelvin (0C + 273) Water Potential practice = s + p
A cell is in equilibrium with its surroundings.The molarityof the surrounding solution is 0.5M, and the temperature is200C. s = -(1)(.5)(.0831)(273+20) = bars -12.2 bars Because we dont know the pressure potential (turgorpressure). If the cell is flaccid, then the solute potential is bars because the pressure potential is zero. s =-iCRT i ionization constant (assume i = 1) C molar concentration (mol/L) R pressure constant( L-bars/mol-K) T temperature in Kelvin (0C + 273) (1/5) Group BR: Transpiration
Describe the process of transpiration in plants. Explain how capillary action works in plants. Leaves have openings called stomata, sometimes up to per mm2. Which 3 gases enter or exit through thestomata when they are open? Would you expect stomata to open more often duringthe day or at night? Explain. Left: Guard cellsswollen and open Right: Guard cellslose water and close Stomata Transpiration A 15 m tall maple tree has ~177,000 leaves with a totalsurface area of 675 m2. During a summer day, it loses 220 L ofwater PER HOUR via transpiration! So to prevent wilting thexylem must transport that much water up from the roots to theleaves EVERY HOUR. How? TACT! Transpiration Adhesion Cohesion Tension (negative pressure potential) How does water reach the leaves of a plant? TACT!!
Transpiration Adhesion Cohesion Tension(negativepressurepotential) Transpiration How do you think humidity affects the rate of water lossfrom leaves through stomata? Think about the factorsthat govern the movement/diffusion of water.