assisted membrane transport

Question 1

what are the 2 different mechanism for assisted/selective transport of ions/molecules across cell membrane

Answer 1

carrier-mediated transport and vesicular transport

Question 2

what type of molecules would require assisted transport

Answer 2

ions moving against conc. gradient, poorly lipid soluble/polar molecules

Question 3

describe the mechanism of carrier-mediated transport and the characteristics that determine the amount of material transported

Answer 3

substance binds to specific carrier which undergoes conformational change to transport substance
characteristics = specificity, saturation and competition

Question 4

state the 2 forms that carrier-mediated transport comes in

Answer 4

active and facilitated(passive) transport

Question 5

describe the difference between active and facilitated(passive) transport

Answer 5

active = requires energy to transport substance 'uphill' against the conc. gradient
facilitated/passive = doesn't require energy, uses a carrier to facilitate movement of substance from high to low conc. gradient ('downhill')

Question 6

describe the 2 forms that active transport comes in

Answer 6

primary active transport = energy is required to move substance against conc. gradient
secondary active transport = energy is required but not directly used to move substance ‘uphill’

Question 7

describe how a secondary active transport movement works

Answer 7

carrier does not split the ATP, uses stored secondhand energy from an ion gradient (usually Na+) to move substance uphill

Question 8

describe the mechanism for the NaK pump and give 3 important roles of the NaK pump

Answer 8

the pump moves 3 Na+ ions out of the cell for every 2 K+ ions into the cell
1- helps establish Na+ and K+ ion gradient across membrane
2- helps regulate cell volume, by controlling conc. of solute inside the cell
3- energy used to drive pump indirectly serves as energy source for secondary active transport

Question 9

describe the 2 mechanisms secondary active transport can occur by

Answer 9

symport(co-transport) = the solute and Na+ move in same direction
antiport = the solute and Na+ move in opposite directions

Question 10

state the 2 types of vesicular transport and whether or not it is an active or passive transport

Answer 10

active transport

exocytosis and endocytosis