diffusion / osmosis / dialysis

Brownian motion :: Microscopic

random movement of individual particles in a fluid

Brownian motion and entropy :: It drives the spreading out of matter

contributing to the natural tendency toward disorder

Brownian motion and diffusion :: It causes particles to spread from crowded areas to less crowded areas

Diffusion in a cell diagram :: Solutes start clumped (high concentration) and spread by random thermal motion until evenly distributed (equilibrium)

Solute :: A substance dissolved in a liquid (solvent)

Solute examples from lecture :: Glucose

sodium ions

Selectively permeable membrane :: Lets certain molecules/ions pass freely while blocking others based on size

charge

Concentration gradient :: Gradual difference in solute concentration between two regions

Why concentration gradients matter to cells :: Drive transport

store potential energy

Meaning of "net" in net diffusion/osmosis/dialysis :: The directional outcome: difference between particles moving one direction versus the opposite

Passive transport :: Moves molecules down their concentration gradient; no cellular energy needed (simple diffusion

facilitated diffusion

Active transport :: Moves molecules against their gradient; requires ATP and transport proteins (sodium-potassium pump

exocytosis

Can passive transport move solutes up a gradient? :: No; it only moves substances down their gradient

Osmosis figure: when is volume between X and Y equal? :: At the start

before net osmosis shifts water

Osmosis figure: when is solute concentration in Y equal to X? :: After 60 minutes

Osmosis figure: when is pressure on the membrane equal? :: After 60 minutes of osmosis

Hypertonic solution/cell :: Higher solute concentration

Hypotonic solution/cell :: Lower solute concentration

Direction of net osmosis :: Water moves toward the hypertonic side (higher solute concentration)

Direction of net dialysis :: Solutes move from high solute concentration toward low solute concentration (down their gradient)

Turgor pressure :: Pressure of fluid contents inside a plant cell pushing outward against the cell wall

How turgor pressure affects passive transport :: High turgor creates back-pressure that counteracts osmotic pressure

influencing net water movement into the cell

Red blood cell in hypotonic solution :: Swells

Red blood cell in isotonic solution :: Normal/stable

Red blood cell in hypertonic solution :: Shrivels

Plant cell in hypotonic solution :: Turgid/firm/normal

Plant cell in isotonic solution :: Limp

Plant cell in hypertonic solution :: Cell membrane pulls away from the cell wall