Day 14 DO NOW: What happens when you put salt on a slug or a snail? AIM: What is Osmosis?

Day 14DO NOW: What happens when you

put salt on a slug or a snail?

AIM: What is Osmosis?

http://www.youtube.com/watch?v=PiQkebrCw8U

What is osmosis?• Osmosis is the diffusion of water through a

membrane. • Like regular diffusion, water will move from

one concentration to another until both sides are equal in concentration

10 Salt20 Water

20 Salt10 water

20 Salt

20 water

10 Salt

10 Water

How is osmosis different than diffusion?

• In diffusion, the solute (the dissolved material) moves from a high concentration to a low concentration.

• Remember that the solute is small molecules such as glucose, fatty acids, amino acids, oxygen, carbon dioxide and water.

• But because some molecules are too big to get across the membrane, water has to move in toward these large molecules in order to dilute the concentration.

What are the effects of osmosis? (a)

• If the concentration of water inside the cell and outside the cell is the same, there is no net osmosis occurs.

Water goes in

Water goes out

What are the effects of osmosis? (b)

• If the concentration of water is higher outside the cell then inside the cell, the water outside the cell will move inside the cell.

Water goes in (only) Pop!!

What are the effects of osmosis? (c)• If the concentration of water is higher inside

the cell then outside the cell, the water inside the cell will move outside the cell.

Water comes out (only)

How does osmosis affect plant cells?

• All cells goes through osmosis.• Because plant cells have a cell wall

surrounding it, the cell looks differently when osmosis occurs.

If the plant cell is placed in a solution of high concentration of solute……

then the water will leave the cell causing the cytoplasm to shrink.

The cell wall remains the same!!

If the plant cell is placed in a solution of low concentration of solute……

then the water will enter the cell causing the cytoplasm to swell.

The cell wall begins to swell, deforming the shape!!

• http://www.youtube.com/watch?v=rvIh8JvyaYA

Day 15What is Passive and Active

Transport?

DO NOW: How would you define someone who is active? ____________________How would you define someone who is passive? ___________________________

There are 2 ways molecules can get in a cell.

• 1) Passive Transport – This type of transport requires no energy (no ATP). The cell uses the natural process of different concentration and molecule size to help molecules move from one area to another.

How to Remember Passive Transport

Greater Concentration

Lesser Concentration

Examples:

Diffusion

Osmosis

Energy (ATP)

• 2) Active Transport – This type of transport requires energy (ATP) to move molecules across the membrane. Some molecules must go against the concentration grain, therefore they rely on protein “pumps”. To get them across.

There are 2 ways molecules can get in a cell. (cont)

Active transport that requires energy. Movement molecules from low concentration to high.

Greater Concentration

Lesser Concentration

Need Energy (ATP)

How to Remember Active Transport

•Phagocytosis- Movement of large material into the cell. Cell “pinches” the membrane forming a “bubble” around the large material.

Other Type of Active Transport

Why is Cellular Transport Important?

• Cells need materials in order to carry out the 8 life functions• Cells need O2 and glucose to perform respiration•Cells need to get rid of waste products (CO2 & excess water)•Cells need to grow and repair itself•Cells need molecules to break apart and recombine to make new molecules.

•Without cellular transport, cells could not do what they do.

Type of cellular Transport

Energy / No Energy

High to low

Low to high

Special circumstances

Diffusion No energy High to low Small molecules

Osmosis No energy High to low water

Passive Transport

No energy High to low Diffusion/ osmosis

Active Transport Energy (ATP) Low to high Large molecules / cell doesn’t want

Phagocytosis Energy Large particle Cell engulfs large particles

Red Onion in tap water

Red Onion in distilled water starting to rehydrate

Red Onion eventually goes back