Unit 3 – Lecture 3

Diffusion Diffusion – movement of substances from an area of high concentration to an area of low concentration works to balance the concentration gradients of substances ex: perfume in a room, dye in a glass of water…

Diffusion – cont’d Concentration Gradient – difference in concentration of a substance over a certain area “with/down” the gradient = particles move from area of high conc. to low conc.

Diffusion – cont’d Concentration Gradient – difference in concentration of a substance over a certain area “against” the gradient = particles move from area of low conc. to high conc. non-natural movement; requires E

Diffusion – cont’d Dynamic Equilibrium – a balance of the distribution of particles in an area acknowledging the constant movement of the particles dynamic – opposite of sta(tic/sis) indicates constant change

Discuss What is the purpose / point of diffusion? What does it mean to move “against” a concentration gradient? What is dynamic equilibrium?

Diffusion – cont’d Diffusion often occurs through one of two types of membranes: permeable membrane allows all molecules [solute, solvent, or other particle] to pass through semi/selectively permeable membrane allows only certain substances to pass through

Discuss What type of membrane, permeable or selectively permeable, do our cells have?

Diffusion Drawings #1 Problem: In a beaker with a permeable membrane there are: 4 particles of X [3 left, 1 right] 12 particles of O [2 left, 10 right] Based on the given information, identify & understand the type of membrane draw before & after beaker with membrane

Problem: In a beaker with a permeable membrane there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] Based on the given information, identify & understand the type of membrane draw before & after beakers with membrane

Problem: In a beaker with a permeable membrane there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] before beaker: under beaker, record # of particles per side draw # particles in beaker X = 3X= 1 O = 2O = 10

Problem: In a beaker with a permeable membrane there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] before beaker: determine directions of particle movement above, draw arrows specifying how particles will move X = 3X= 1 O = 2O = 10

Problem: In a beaker with a permeable membrane there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] before beaker: large arrow = larger movement [specify type of particle] X = 3X= 1 O = 2O = 10 X O

Problem: In a beaker with a permeable membrane there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] before beaker: small arrow = smaller movement [specify type of particle] X = 3X= 1 O = 2O = 10 X O

Problem: In a beaker with a permeable membrane there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] after beaker: under beaker, record new # of particles per side X = 3X= 1 O = 2O = 10 X X = 2X= 2O = 6 O

Problem: In a beaker with a permeable membrane there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] after beaker: draw # of particles in beakers X = 3X= 1 O = 2O = 10 X X = 2X= 2O = 6 O

Problem: In a beaker with a permeable membrane there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] after beaker: draw appropriate arrows [specify type of particle] X = 3X= 1 O = 2O = 10 X X = 2X= 2O = 6 O X O

Diffusion Drawings #2 Problem: In beaker with a membrane selectively permeable to X molecules, there are: 4 particles of X [3 left, 1 right] 12 particles of O [2 left, 10 right] Based on the given information, identify & understand the type of membrane draw before & after beaker with membrane

Problem: In a beaker with a membrane selectively permeable to X molecules, there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] Based on the given information, identify & understand the type of membrane draw before & after beakers with membrane

Problem: In a beaker with a membrane selectively permeable to X molecules, there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] before beaker: under beaker, record # of particles per side draw # particles in beaker X = 3X= 1 O = 2O = 10

Problem: In a beaker with a membrane selectively permeable to X molecules, there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] before beaker: determine directions of particle movement above, draw arrows specifying how particles will move X = 3X= 1 O = 2O = 10

Problem: In a beaker with a membrane selectively permeable to X molecules, there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] before beaker: large arrow = larger movement [specify type of particle] X = 3X= 1 O = 2O = 10 X

Problem: In a beaker with a membrane selectively permeable to X molecules, there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] before beaker: small arrow = smaller movement [specify type of particle] X = 3X= 1 O = 2O = 10 X

Problem: In a beaker with a membrane selectively permeable to X molecules, there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] after beaker: under beaker, record new # of particles per side X = 3X= 1 O = 2O = 10 X X = 2X= 2 O = 2O = 10

Problem: In a beaker with a membrane selectively permeable to X molecules, there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] after beaker: draw # of particles in beakers X = 3X= 1 O = 2O = 10 X X = 2X= 2 O = 2O = 10

Problem: In a beaker with a membrane selectively permeable to X molecules, there are: 4 particles of X [3 left, 1 right]; 12 particles of O [2 left, 10 right] after beaker: draw appropriate arrows [specify type of particle] X = 3X= 1 O = 2O = 10 X X = 2X= 2 O = 2O = 10 X

Osmosis Osmosis – diffusion of water across a selectively permeable membrane membrane allows ONLY water to go through solute particles NEVER move water must be used to reach dynamic equilibrium more water moves to where there is more solute

Discuss Which has the higher concentration of solute? 5 scoops of lemonade in a pitcher filled with 8 ounces [1 cup] of water 5 scoops of lemonade in a pitcher filled with 1 gallon of water How can you make the concentrations equal?

Osmosis Drawings Problem : With a membrane selectively permeable to water, there are: 4 particles of X [3 left, 1 right] Based on the given information, identify & understand the type of membrane draw before & after tubes with membrane

Problem: With a membrane selectively permeable to water, there are: 4 particles of X [3 left, 1 right] Based on the given information, identify & understand the type of membrane draw before & after tubes with membrane

Problem: With a membrane selectively permeable to water, there are: 4 particles of X [3 left, 1 right] before tube: under tube, record # of particles per side draw # particles in tube X = 3X= 1

Problem: With a membrane selectively permeable to water, there are: 4 particles of X [3 left, 1 right] before tube: determine directions of particle movement X = 3X= 1

Problem: With a membrane selectively permeable to water, there are: 4 particles of X [3 left, 1 right] before tube: above, draw arrows specifying how particles will move X = 3X= 1

Problem: With a membrane selectively permeable to water, there are: 4 particles of X [3 left, 1 right] before tube: large arrow = larger movement [specify type of particle] X = 3X= 1 H2OH2O

Problem: With a membrane selectively permeable to water, there are: 4 particles of X [3 left, 1 right] before tube: small arrow = smaller movement [specify type of particle] X = 3X= 1 H2OH2O

Problem: With a membrane selectively permeable to water, there are: 4 particles of X [3 left, 1 right] after tube: under tube, record # of particles per side X = 3X= 1 H2OH2O

Problem: With a membrane selectively permeable to water, there are: 4 particles of X [3 left, 1 right] after tube: draw # of particles in beakers AND water level X = 3X= 1 H2OH2O

Problem: With a membrane selectively permeable to water, there are: 4 particles of X [3 left, 1 right] after tube: draw appropriate arrows [specify type of particle] X = 3X= 1 H2OH2O H2OH2O

What happens to cells? Hypertonic Solution – solution outside of the cell has a higher concentration of solute than inside of the cell. “hyper” = more than normal water moves out of cell cell shrinks Why is this bad for the cell?

What happens to cells? – cont’d Isotonic Solution – solution outside of the cell has the same concentration as the solution inside of the cell. concentrations are equal [“iso”] cell remains the same size

What happens to cells? – cont’d Hypotonic Solution – solution outside of the cell has a lower concentration of solute than inside of the cell. “hypo” = less than normal water moves into the cell cell swells animal cell – may burst plant cell – rigid [preferred for plants]

Discuss Hypertonic, Hypotonic, Isotonic Compare each term [how are they similar?]. Contrast each term [how are they different?].