membranes

Question 1

components of membrane?

Answer 1

plb
proteins (integral, peripheral, membrane anchored)
glycolipids and glycoproteins (signalling)
cholesterol

Question 2

purposes of membrane proteins?

Answer 2

transport
signalling
enzymes
joining cells to each other and to the ECM

Question 3

4 ways in which membrane protein activity is regulated?

Answer 3

ligand gated: ligand needs to bind to protein receptor to activate it
voltage gated: protein active when voltage drop across membrane is above threshold level
energy dependent: protein operates when sufficient ATP is available
physical stretching

Question 4

4 examples of active transport?

Answer 4

electrogenic pumps
Na+/K+ pumps
sucrose-H+ transprot system
ATP synthase pump

Question 5

describe electrogenic pumps

Answer 5

• plants fungi bacteria

- actively transport H+ ions out of cell to make conc and voltage gradient

Question 6

describe Na+/K+ pump

Answer 6

antiport pump
Na+ binds to protein
ATP breaks down, Pi attaches to protein
protein changes shape
Na+ goes out of cell
K+ binds to protein
Pi released
protein changes shape
K+ goes into cell

Question 7

describe sucrose-H+ transport system

Answer 7

active transport pump transports H+ out of cell
H+-sucrose cotransporter lets H+ flow down conc gradient, creating energy for sucrose to go into cell against conc gradient

Question 8

describe ATP synthase pump

Answer 8

H+ transproted to intermembrane space, breaking down NADH

H+ flows back down along conc gradient which enables synthesis of ATP

Question 9

classes of pumps?

Answer 9

uniport (one particle)
symport (2 particles in same direction)
antiport (2 particles in opposite direction)