1.4 Membrane transport

Question 1

Types of movement through membrane

Answer 1

1. Simple diffusion
2. Facilitated diffusion
3. Osmosis
4. Active transport

Question 2

Simple diffusion

Answer 2

SIMPLE DIFFUSION: net movement of particles from high conc to low conc until equilibrium is reached

DOWN the concentration gradient

Particles: non-polar/hydrophobic, small - CO2, O2, glucose

Question 3

Facilitated diffusion

Answer 3

FACILITATED DIFFUSION: diffusion through protein channels in membrane

DOWN the conc gradient (one channel - one type of particle)

Particles: large, polar/hydrophilic - sugars, ions, water (aquaporins)

Question 4

Osmosis

Answer 4

OSMOSIS: diffusion of water thorugh semi-permeable membrane from low solute conc to high solute conc until equilibrium is reached

Question 5

How do substances dissolve?

Answer 5

By forming intermolecular bonds with water molecules

Question 6

Osmolarity

Answer 6

OSMOLARITY: measurement of the amount of solute particles in a solvent

Water potential - the ability /potential of water to move around

Osmotic control is important in otransplant organ bathing

Question 7

Types of solutions

Answer 7

HYPERTONIC: higher osmolarity, crenation (RBC), plasmolysis (plant)

ISOTONIC: same osmolarity, nothing (RBC), flaccid (plant)

HYPOTONIC: lower osmolarity, lysis (burst) (RBC), turgid (plant)

Question 8

Active transport

Answer 8

ACTIVE TRANSPORT: the movement of particles AGAINST conc gradient using ENERGY (ATP)

Proteins pumps (specific to molecules) - hydrolysis of ATP causes conformational change - translocate molecules against the gradient - maintains gradient

Ex: Na-K pumps in neuron axons (maintains the gradient 3Na+ out - 2K+ in

Question 9

Endocytosis - Exocytosis

Answer 9

ENDOCYTOSIS: vesicles form, membrane pinches off, material into the cell, conatins water and solute that cant pas through membrane

EXOCYTOSIS: vesicles fuse with membrane, releases content outside - secretion/expel waste