“Salad” Notes Movement of molecules in and out of the cell 10/2014

Natural Movement of Molecules Concentration: the strength of a solution. Concentration Gradient: Describes a situation of solutions with different concentrations in a space. Molecules move from High concentration to Low concentration

Passive Transport The movement of substances across the cell membrane without the use of energy Flows from high concentration to low concentration Includes diffusion, osmosis, & facilitated diffusion

Diffusion Movement from high to low concentration until an equal distribution of those molecules is reached in all areas Movement of ANY small uncharged molecules

Osmosis Diffusion of water from high to low concentration

Tonicity Osmotic pressure AKA turgor when we talked about plants! Hypertonic – higher concentration than internal contents Water leaves cell trying to dilute external concentration Isotonic – same concentration Even water movement Hypotonic – lower concentration than internal contents Water moves into cell to dilute internal concentration

Tonicity

Facilitated Diffusion A carrier protein moves the molecules across the cell membrane down the concentration gradient.

Active Transport Movement from low to high concentration Requires ENERGY & a transport protein