2.18 Osmosis

Osmosis

net movement of water molecules from a region of lower solute concentration to a region of higher solute concentration through a partially permeable membrane (dilute solution to a concentrated solution)

Water molecules will move from an area of…

more free water molecules to an area of fewer free water molecules

Free water moelcules

single, isolated molecule of water that is not bound to or interacting with any other molecules, ions, or surfaces.

Why can water molecules still pass through the bilayer?

although they are polar they are small enough to pass

Cytoplasm +osmosis

• constantly effect’s cells of living organism

• Cell cytoplasm = water and dissolved substances

• lose or take on water depending on the number of free water molecules in their surroundings in comparison to their cytoplasm

Hypertonic solution

• concentration outside > inside

• water moves out

• cell looses water + shrinks

• cell membrane pulls away from wall

• PLASMOLYSED

Isotonic solution

• concentration outside = inside

• water moves in & out at equal rates

• no net movement

• FLACCID

Hypotonic solution

• concentration outside> inside

• water moves into cell

• vacuole swells

• TURGID