+ diffusion particles in a solution move from an area of more concentration to an area of less...

+DiffusionParticles in a solution move from an area

of more concentration to an area of less concentration.

Particles must be small to cross the cell membrane.

No proteins are required Sometimes channel proteins help

No Energy is required.

More concentration

Less concentration

+Diffusion

Particles will move from an area of high (more) concentration to an area of low (less) concentration until EQUILIBRIUM is reached.

+Equilibrium

Equal amounts of solute on both sides of a membrane.

Even when equilibrium is reached, particles will continue to diffuse in both directions, but the concentration won’t change.

+Semi - Permeable Membrane

Some substances can pass across and others cannot.

+Osmosis

Osmosis is the diffusion of water through a selectively permeable membrane.

Small water molecules move from an area of greater water concentration (more pressure) to an area of lesser water concentration (less pressure).

No proteins are required but they often help.

Sometimes aquaporin proteins help.

No Energy is required.

+Osmosis

www.biologycorner.com/resources/osmosis.jpg

Isotonic

+Potato Slice Set-up

Procedure:

Feel the texture of the potato slices. Record your observations in the data table on the worksheet. (You only need to fill in the gray boxes now because all potatoes should feel the same at the start of the experiment).

Put one slice into a petri dish of distilled water, one slice into a petri dish of salt water and the leave the third slice in the tray exposed to air. Record the time in the data table below.

Wait for one hour: You will be visiting the rest of the stations and finishing the notes during this time.

+ Distilled Water Salt water

+Egg Osmosis Lab

Observe the egg in the container labeled “observation egg.” You can pick the egg up but please be gentle. It will break!

This egg has had the shell dissolved off in vinegar. What you are touching is the cell membrane of the egg. It is semi-permeable and thus will let some materials in and out of the cell but not all.

Pick up an Egg Osmosis Lab worksheet and complete questions 1-7. Use the definitions on the slide to help you.

Fill in the original circumferences provided in the data table. We will finish this lab tomorrow.

+Egg without Shell

+Eggs in different solutions

+Types of Solutions

Isotonic solution: Same strength The solute concentration is the same inside

and outside the cell.

Hypertonic solution: Above strength The solute concentration is higher in in the

solution surrounding the cell than inside.

Hypotonic solution: Below strength The solute concentration is lower in the

solution surrounding the cell than inside.

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+Passive Transport

Facilitated diffusion is the passive transport of materials transport proteins.

Passive means that no energy is needed.

Move from high concentration to low

No ENERGY is required.

The particles are too big for normal diffusion so they pass through protein channels in the membrane.

+Facilitated Diffusion

+Different types of proteins can help.

+Active Transport

Active Transport: Materials move against a concentration gradient.

(Less concentration to more concentration) ENERGY!! (ATP) is required.

Protein “pumps” use energy to change

shape and push materials

across the membrane.

More concentration

Less concentration

Energy

+ Active (energy) vs Passive (no energy)

+Active Transport by the Cell Membrane

Endocytosis: a cell takes material into the cell by infolding of the cell membrane. No proteins needed because cell membrane

folds to enter cell. Phagocytosis: cell-eating (food vesicles)

Exocytosis: moving large molecules across the membrane out of the cell.

Both require a lot of Energy!!!

+Exocytosis – leaving the cell

+Endocytosis – entering the cell

+