3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

Somewhere on pg. 28Somewhere on pg. 28

If the cell membrane was rigid (solid or hard), as opposed to fluid (oil or liquid like), explain why the membrane would no longer be selectively permeable.

If the membrane was rigid:

• The phospholipids would not be able to move from side to side or slide past one another

• The phospholipids would be unable to move to allow material in or out!

3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

3.3 Cell MembraneSponge: Set up Cornell Notes on pg. 31

Topic: 3.4 Diffusion

Essential Question:

Explain what a concentration gradient is and what it means for a molecule to diffuse down its concentration gradient.

2.1 Atoms, Ions, and Molecules

Explain what a concentration gradient is and what it means for a molecule to diffuse down its concentration gradient.

3.4 Diffusion

Key Concept: Materials move across membranes because of concentration differences.

3.3 Cell Membrane

Standard

1.a Students know cells are enclosed within a semipermeable membranes that regulate their interaction with their surroundings.

3.4 Diffusion and Osmosis

KEY CONCEPT Materials move across membranes because of concentration differences.

3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

Solution: A homogenous mixture of two or more substances, which may be solids, liquids, or gases, or the combination of these.

Ex: Sugar water

Solute: Substance dissolved in another substanceEx: Sugar

Solvent: Substance doing the dissolving (usually the substance present in the greatest amount)

Ex: Water (THE BEST SOLVENT)

Which one is theWhich one is the Solute Solute? ? SolventSolvent? ? SolutionSolution??

Milk Chocolate Milk Chocolate Syrup

Air Nitrogen (78%) Oxygen, argon, CO2 (22%)

Solvent

Solvent

Solution

Solution

Solute

Solute

• Passive transport- the movement of molecules across a cell membrane without energy input from the cell

• There are two types of passive transport.

2. osmosis

1. diffusion

3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

Diffusion Demonstration Diffusion Demonstration

Materials: 2 Cups, Water, Dye, Salt, GraphMaterials: 2 Cups, Water, Dye, Salt, Graph

1)1) Identify the solvent, solute, and solution for Identify the solvent, solute, and solution for each demonstrationeach demonstration

2)2) Hypothesize what is going to happen when Hypothesize what is going to happen when you drop the food coloring in the water. Salt you drop the food coloring in the water. Salt in the water?in the water?

3)3) Did your hypothesis match the results?Did your hypothesis match the results?

4)4) Explain how these experiments Explain how these experiments demonstrated diffusiondemonstrated diffusion

  Colored H2O Salt Water

Solvent   

 

Solute   

 

Solution   

 

Hypothesis: What is going to happen when….

Dye is added      

Salt is added

What happened after 5 mins? Was your hypothesis right?

       

 

How did these experiments demonstrate diffusion?

      

 

Pg. 30

Diffusion: is the movement of molecules in a fluid or gas from a region of higher concentration to a region of lower concentration.

3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

Diffusion: is the movement of molecules in a fluid or

gas from a region of higher concentration to a region of lower concentration.

3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

Diffusion: is the movement of molecules in a fluid or gas from a region of higher concentration to a region

of lower concentration.

3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

Air Freshener Demo.Air Freshener Demo.

• Concentration gradient- the difference in the concentration of a substance from one location to another.

•Molecules diffuse down their concentration gradient

Top ¼ pg. 30

3.3 Cell MembraneSponge: Set up Cornell Notes on pg. 33

Topic: 3.4 Osmosis

Essential Question:

A cell is bathed in fluid. However, you notice that water is flowing out of the cell. In what kind of solution is this cell immersed?

2.1 Atoms, Ions, and Molecules

A cell is bathed in fluid. However, you notice that water is flowing out of the cell. In what kind of solution is this cell immersed?

3.4 Osmosis

3.3 Cell Membrane

Isotonic Solution Hypertonic Solution Hypotonic Solution

Pg. 32

• Osmosis is the diffusion of water molecules across a semipermeable membrane.

3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

The water will continue to move across the The water will continue to move across the membrane until it reaches “equilibrium” or membrane until it reaches “equilibrium” or an isotonic statean isotonic state

• There are three types of solutions.

3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

• Same amount of solutes/water inside and outside cell

• = amounts of water enter and leave the cell

• Stays the same size!

• There are three types of solutions.

3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

• More solutes outside the cell than inside the cell

• More water inside the cell than outside the cell

• More water exits cell• Shrinks!

• There are three types of solutions.

3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

• More solutes inside

the cell than outside the cell

• More water outside cell than inside the cell

• More water enters cell• Expands!

Osmosis VideosOsmosis Videos

• Osmosis vs. DiffusionOsmosis vs. Diffusion• Osmosis Computer GraphicsOsmosis Computer Graphics• Osmosis Demo VideoOsmosis Demo Video• Osmosis with a U-tubeOsmosis with a U-tube

Predictions Conclusion

Sugar Water   

    

Distilled Water     

Salt Water     

.

Table 1: Predictions and Conclusions

Gummi Bear Osmosis LabGummi Bear Osmosis Lab

Starting Information

Weight (g) Length (mm) Width (mm)

Osmosis Lab MaterialsOsmosis Lab Materials

Materials: Materials:

1 cup Water Sugar1 cup Water Sugar

1 Gummi Bear Scale (g)1 Gummi Bear Scale (g)

Ruler (mm) String (for width)Ruler (mm) String (for width)

SaltSalt

1)1) Label each cup: First/Last Name Period # Label each cup: First/Last Name Period #

Day One: Gathering DataDay One: Gathering Data

1)1) Weigh your Gummi Bear and record its weight Weigh your Gummi Bear and record its weight (g)(g)

2)2) Measure your Gummi’s length and width (mm)Measure your Gummi’s length and width (mm)

3)3) Place the Gummi in a 25/75 sugar/water Place the Gummi in a 25/75 sugar/water solutionsolution

4)4) Fill in your table with your hypothesisFill in your table with your hypothesis

Day Two: Gathering DataDay Two: Gathering Data

1)1) Dry your Gummi bear off carefullyDry your Gummi bear off carefully

2)2) Weigh your Gummi Bear and record its weight (g)Weigh your Gummi Bear and record its weight (g)

3)3) Measure your Gummi’s length and width (mm)Measure your Gummi’s length and width (mm)

4)4) Was your hypothesis correct? What happened to your Was your hypothesis correct? What happened to your Gummi? Compare this data with your group data, and Gummi? Compare this data with your group data, and record on Lab report tables.record on Lab report tables.

5)5) Rinse out your cup and rinse off your gummi (quick and Rinse out your cup and rinse off your gummi (quick and carefully)carefully)

6)6) Place the Gummi in a 100% distilled waterPlace the Gummi in a 100% distilled water

7)7) Fill in your table with your new hypothesisFill in your table with your new hypothesis

Day Three: Gathering DataDay Three: Gathering Data

1)1) Dry your Gummi bear off carefullyDry your Gummi bear off carefully

2)2) Weigh your Gummi Bear and record its weight (g)Weigh your Gummi Bear and record its weight (g)

3)3) Measure your Gummi’s length and width (mm)Measure your Gummi’s length and width (mm)

4)4) Was your hypothesis correct? What happened to Was your hypothesis correct? What happened to your Gummi? Compare this data with your group your Gummi? Compare this data with your group data, and record on Lab report tables.data, and record on Lab report tables.

5)5) Rinse out your cup and rinse off your gummi (quick Rinse out your cup and rinse off your gummi (quick and carefully)and carefully)

6)6) Place the Gummi in a 25/75 solution of salt and waterPlace the Gummi in a 25/75 solution of salt and water

7)7) Fill in your table with your new hypothesisFill in your table with your new hypothesis

• Some molecules cannot easily diffuse across the cell membrane Ex: H2O

• Facilitated diffusion is diffusion through transport proteins

• Things like H2O would be repelled by the phospholipid tails, so transport proteins allow the H2O to diffuse easily

3.4 Diffusion and Osmosis3.4 Diffusion and Osmosis

Pg. 32 Diffusion and Osmosis Video NotesPg. 32 Diffusion and Osmosis Video Notes

• Osmosis in the kitchenOsmosis in the kitchen• Osmosis with an EggOsmosis with an Egg• Desalination- Reverse OsmosisDesalination- Reverse Osmosis