Chapter 5 Notes Homeostasis and Cell Transport

Diffusion The movement of molecules from an area of high concentration to an area of low concentration. *(PASSIVE)

Concentration Gradient The difference in the concentration of molecules across a distance Equilibrium Reached when the concentration of molecules is the same throughout the space the molecules occupy

Diffusion Animation hill.com/sites/ /student_view0/chapter2/animation__how_diffusion_works.ht ml hill.com/sites/ /student_view0/chapter2/animation__how_diffusion_works.ht ml

Osmosis The process by which water molecules diffuse across a membrane from an area of higher concentration to an area of lower concentration. *(PASSIVE)

Solvent– usually water (does the dissolving) Solute – stuff that gets dissolved Only some things can pass through

Hypertonic Relative term When concentration of solute is higher (water is lower) than area of interest OUTSIDE: 78% Solute 22% Water INSIDE: 19% Solute 81% Water

Hypotonic Relative term When concentration of solute is lower (water is higher) than area of interest OUTSIDE: 25% Solute 75% Water INSIDE: 82% Solute 18% Water

Isotonic Relative term When concentration of solute (and water) is the same as the area of interest INSIDE: 50% Solute 50% Water OUTSIDE: 50% Solute 50% Water

Osmosis Animation hill.com/sites/ /student_view0/chapter2/animation__how_osmosis_works.htm l hill.com/sites/ /student_view0/chapter2/animation__how_osmosis_works.htm l

Use this link to fill in the chart: IntracellularExtracellular SoluteWater (Solvent) SoluteWater (Solvent) Before After Results IntracellularExtracellular SoluteWater (Solvent) SoluteWater (Solvent) Before After Results Cell in HYPOTONIC solution Cell in HYPERTONIC solution

Use this link to fill in the chart: IntracellularExtracellular SoluteWater (Solvent) SoluteWater (Solvent) Before After Results IntracellularExtracellular SoluteWater (Solvent) SoluteWater (Solvent) Before After Results Cell in HYPOTONIC solution Cell in HYPERTONIC solution The cell swells! The cell shrinks!

How do cells deal with osmosis? Turgor Pressure – pressure water molecules exert on cell wall Plasmolysis – when cells shrink away from cell wall & turgor pressure is lost

When stuff is too big (or not soluble in lipids)… Facilitated Diffusion – diffusion through channel/carrier proteins *(PASSIVE)

Active Transport Moving molecules “up” their concentration gradient or from lower to higher concentrations *(ACTIVE)

When stuff is too big (or not soluble in lipids)… Exocytosis – process by which a substance is released from the cell through a vesicle that transports the substance to the cell surface then fuses with the membrane to let the substance out of the cell- *(ACTIVE)

When stuff is too big (or not soluble in lipids)… Endocytosis – cells ingest external fluid, macromolecules and large particles enclosing it in a folded portion of the cell membrane that pinches off to form a vesicle - *(ACTIVE)

Two types of Endocytosis Pinocytosis – involves the transport of fluids (or solutes) * (ACTIVE)

Two types of Endocytosis Phagocytosis – involves the transport of large particles (or whole cells) * (ACTIVE)

Vesicles Endocytosis Exocytosis Summing it up…

Active Transport Sodium – Potassium Pumps – carrier protein uses energy (ATP) to “pump” 3 Na+ ions out and 2 K+ ions in * (ACTIVE) Another animation - urces/animations/ion_pump/ionpump.html

Putting Sodium Potassium Pumps into Action: