primary and secondary active transporters

Question 1

define primary active transport

Answer 1

driven directly by the energy released by hydrolysis of ATP to ADP
as part of the reaction cycle ATP hydrolysis is also catalysed

Question 2

what is co-transport

Answer 2

more than one type of ion or molecule may be transported on a membrane transporter per reaction cycle

Question 3

what is uniport, symport and antiport

Answer 3

uniport is when only one ion/molecule is being transported
symport is two in the same direction
antiport is two in two different directions
symport and antiport is co-transport

Question 4

features of Na+-K+-ATPase pump (sodium pump)

Answer 4

3Na+ out and 2K+ in
Primary active transport
P-type ATPase - ATP phosphorylates aspartate producing phosphoenzyme intermediate this drives initial confirmational changes to allow the transport of ions
generates ion gradients that are used to allow secondary active transport and cation potentials
only small contribution to resting membrane potential

Question 5

define secondary active transport

Answer 5

driven indirectly by the energy released by hydrolysis of ATP to ADP
dissipation of gradients formed for another ion or substance provides the energy for secondary active transport

Question 6

how does Na+-Ca2+- exchanger work

Answer 6

sodium pump c reates a sodium gradient so sodium moves in using the secondary transporter which provides energy for removal of calcium

Question 7

calcium transport through primary and secondary active transport

Answer 7

primary : Ca2+-Mg2+-ATPase. has high affinity but low capacity for calcium
secondary : Na+-Ca2+- exchanger . low affinity but high capacity so important when calcium levels are extremely high

Question 8

examples of co transport systems

Answer 8

Na+-K+-ATPase
Na+-Ca2+-exchange
Na+-H+-exchange
Na+-glucose co-transport