5.3 Diffusion Flashcards
What is the difference between movement internally or externally , passive / active
Internal movement relies on kinetic energy of particles = PASSIVE, external movement IS ACTIVE as it requires external energy
Define diffusion
Diffusion is the net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient
- diffusion is passive and will keep happening until equilibrium
What does equilibriums mean?
How does equilibrium work
Where movement of particles are equal in both directions
2) random movement of particles eventually become an equal distribution of it.
What factors affect the rate of diffusion and why ?
Temp - increase temp= increase kinetic energy of particles = they can move at higher speeds
Distance = decrease distance increases rate of diffusion as less distance a particle has to travel
Concentration gradient = higher concentration gradient leads to a greater movement of particles and thus faster movement of particles Overall
Sa:v , greater this greater rate of diffusion , as more sa = more places for particles to move in
What is difference between simple and facilitated, why need facilitated?
Simple is diffusion in the absence of a barrier or membrane , the reason why facilitated happens is to get this barrier across easier
Basic diffusion across membranes
Oxygen carbon dioxide water?
What makes it selectively permeable
Finally what makes more or less rate of diffusion
- this involves going through phospholipids bilayer which is majority non polar
- thus non polar molecules like o2 and co2 can DIFFUSE THROUGH THE MEMBRANE FREELY DOWN A CONCENTRATION GRADIENT
- now due to hydrophobic area it repels charged ions completely from entering so they can not pass through
- HOWEVER, polar molecules with partial charge can SLOWLY DIFFUSE THROUGH, and the smaller ones at a QUICKER RATE
Membranes are thus described as PARTIALLY PERMEABLE, only lets some go through .
2) surface area plays big role here as more as = more diffusion, also diffusion distance, smaller the better
What is it?
Why is facilitated diffusion needed?
Facilitated diffusion is the act of diffusion through protein channels
2) phospholipid bilayer stop ions and large polar molecules from diffusing , thus a method needs to happen so that these can diffuse
How is facilitated diffusion done
1) carrier protein acting as a sodium potassium pump will actively transport three spodumene ions into the blood
2) This creates a concentration gradient , higher in the blood than cells, thus sodium will passively diffuse down the concentration gradient through a co transporter
3) here, one glucose for every two sodium ions “hitch hike “ and is CO-TRANSPORTED into the cells too, facilitated diffusion
4) here now there is a higher concentration in the cells of glucose than blood, so it can passively diffuse through a protein channel which is HYDROPHILIC
Why is facilitated diffuion a passive process and main difference from simple diffusion!
Facialited = passive as although energy is Süd- external, still dependent on internal energy and movement from area of high concentration to lower concentration
Difference is it uses a channel protein to do so and cotransporter
What does the rate of facilitated diffusion dependent on ?
Standard temperature, conc gradient , membrane surface area, distance
2) but more importantly MORE NUMBER OF CHANNEL PROTEINS AVAILABLE = MORE DIFFUSION POSSIBLE
Distance of cube practical and dialysis tube one
How can you test for rate of diffusion
1) artificial cell made using dialysis tubing
2) different solutions made via serial or prepared solutions
3) place solution in cell
4) record mass
5) add into solutions and after 20 mins take out and reweigh
7) you can see rate of diffusion using indicators for detach like iodine, and benneicts for glucose
Cube agar experiment
Agar made from phenolphthalein and NAoH = pink and alkali
- cubes of different sizes put in HCL
- HCL will react and diffuse making colourless
- leave for a bit, twke out , measure volume of still pink
- calculate percentage diffusion now
