Movement of molecules from an area where there are many to an area where there are few

Selectively Permeable Membrane- [like a strainer] - contains different size openings called pores

- only materials smaller than openings pass through

Diffusion- Movement of molecules from an area where there are many to an area where there are few

Examples: food coloring in water, spraying air freshener

Simple Rule:

Equilibrium/Homeostasis- molecules are equally distributed in an area

CONTINUES UNTIL …….

Osmosis- movement of WATER molecules from an area where there are many to an area where there are few

Plasmolysis- cell membrane shrinking away from cell wall, due to water exiting cell Why?

Salt is a substance that will draw water in its direction. This is why you feel thirsty when you eat something salty.

Simple Rule:

Salt WaterFresh Water Cell Membrane

Plant CellsPlant Cells

100% H2O

97% H2O

90% H2O

97% H2O

Water rushes into cell, keeps cellrigid

Water moves out of cell,Cell membrane pulls away from cell wall

10% NaCl

PLASMOLYSIS

HYPOTONIC CELL HYPERTONIC CELL

HYPO = lessTONIC = solution

HYPER= moreTONIC = solution

100% H2O

90% H2O

95% H2O

100% H2O

- Water rushes into cell- Cell swells and may burst due to lack of cell wall

- Water rushes out of cell-Cell shrinks due to lack of cell wall

HYPOTONIC CELL HYPERTONIC CELL

97% H2O

97% H2O

- Cell does not change, water equal inside and out

Equilibrium/Homeostasis

ISOTONIC CELL

ISO = sameTONIC = solution

Animal cells and water movementAnimal cells and water movement

Active Transport - requires energyEndocytosis- process used by cells to transport large materials [proteins] INTOINTO cell

                                                                                                                                      

Greek terms : ENDO = inside CYTOSIS = relates to cell

Exocytosis- process used by cell to move wastes or other materials OUTOUT of cell

Greek terms : EXO = outside CYTOSIS = relates to cell