4.2 Movement into & out cells

Diffusion: n__ m__ o_ m__ f__ r__ o_ h__ c__ t_ r__ o_ l__ c__ d__ _ c__ g__, a_ _ r__ o_ r__ m__ o_ p__

net movement of mols from regions of higher conc to regions of lower conc down a conc gradient, as a result of random movement of particles

Factors of diffusion
1. s__ of c__ g__: incr = incr rate of diffusion
2. t__: incr = incr E_ = faster = incr rate of diffusion
3. n__: l__ mols need more e__ to move = less rate of diffusion
> n__-p__ mols diffuse e__ thru cell m__ than p__ ones bc they are s__ in non-polar p__ t__
4. s__ a__: incr = more mols can d__

steepness, conc gradient, temp, Ek, nature, larger, energy, non-polar, easily, membrane, polar, soluble, phospholipid tails, surface area, diffuse

Surface area : volume
> a larger cell = __(more/less) s.a. : vol

less

Facilitated diffusion
> diffusion thru a t__ p__ (ch__/c__) in a cell m__
> for l__ p__ mols (e.g. glucose/amino acid) that can’t diffuse thru p__ b__
> also for i__ ;; is p__

transport proteins, channel, carrier, membrane, large polar, phospholipid bilayer, ions, passive

Channel proteins
> f__ s__ w/ w__-filled p__ where s__ h__ ions/mols can pass via f__ d__ OR a__ t__
> has ‘gates’: inside can m__ to o__/close pore = c__ ion exchange

fixed shape, water, pores, specific hydrophilic, facilitated diffusion, active transport, move, open, control

Carrier proteins
> can c__ s__ to allow s__ ions/mols to pass via f__ d__ OR a__ t__
> opens on 1 s__ first, then the other when s__ changed
> direction of movement determined by rel. c__ of each side of membrane (h__ → low)

change shape, specific, facilitated diffusion, active transport, side, shape, conc, high

Osmosis: n__ d__ o_ w__ f__ _ r__ o_ h__ w__ p__ t_ _ r__ o_ l__ w__ p__ t__ _ p__ p__ m__

net diffusion of water from a region of higher water potential to a region of lower water potential thru a partially permeable membrane

Water potential, ψ (kPA)
> decr. ψ (i.e. _ve) = __(higher/lower) water potential
> pure water has ψ = __kPa
> factors:
>> conc. soln = __(higher/lower) ψ
>> pressure = __(higher/lower) ψ

-, lower, 0, lower, higher

Osmosis in animals
> no c__ w__ = can shrink/burst
> burst: soln ψ _ cell (h__)
> shrink: soln ψ _ cell (h__)
> same ψ: i__

cell wall, >, hypotonic, <, hypertonic, isotonic

Osmosis in plants
> has c__ w__ = doesn’t burst
> turgid: soln ψ _ cell
>> cell wall resists expansion of p__ (living c__ in cell excl. cell wall)
>> incr p__ in cell = incr ψ until e__
> plasmolysed: soln ψ _ cell
>> p__ shrinks until exerting no p__ on cell wall
>> eventually decr cell ψ to equilibrium

cell wall, >, protoplast, contents, pressure, equilibrium, <, protoplast, pressure

Active transport: m__ o_ m__ t__ t__ p__ a__ _ c__ m__, a__ t__ c__ g__, u__ e__ f__ A__

movement of mols thru transport proteins across a cell membrane, against their conc gradient, using energy from ATP

Active transport
> e__ allows c__ p__ to change s__ (nothing to do w/ channel protein)

energy, carrier protein, shape

Endocytosis
> bulk m__ of l__/s__ i__ a c__ by i__ of cell m__ to make v__ containing the subst., using e__ from A__

movement, liquid/solid into, cell, infolding, membrane, vesicles, energy, ATP

Exocytosis
> bulk m__ of l__/s__ o__ of a c__ by f__ v__ containing the subst. w/ cell m__, using e__ from A__

movement, liquid/solid out, cell, fusing vesicle, membrane, energy, ATP

yes/no:

Feature	Passive movement			Active movement
	Diffusion	Osmosis	Facilitated diffusion	Active transport	Endo/exocytosis
Needs energy

no, no, no, yes, yes

yes/no:

Feature	Passive movement			Active movement
	Diffusion	Osmosis	Facilitated diffusion	Active transport	Endo/exocytosis
Movement of indiv. mols/ions

yes, yes, yes, yes, no

yes/no:

Feature	Passive movement			Active movement
	Diffusion	Osmosis	Facilitated diffusion	Active transport	Endo/exocytosis
Movement thru transport proteins

no, no, yes, yes, no