Block 2 Lecture 22

Question 1

what is the source of energy in secondary active transport

Answer 1

the potential energy available in the transmembrane gradient of one or more other solutes

Question 2

what is coupled transport

Answer 2

the downhill movement of one substrate serving to drive the uphill movement of another. coupled gradients are in opposite directions

Question 3

what is the most commonly used solute gradient for secondary active transport

Answer 3

the inwardly directed Na+ gradient

Question 4

what is the Na-D glucose cotransport (SGLTs)

Answer 4

secondary active transporter, net glucose transport occurs as a result of an inwardly directed chemical gradient for glucose
-couples the flow of Na+ and glucose

Question 5

what is the driving force for SGLTs

Answer 5

the chemical gradient for Na+ and the electrical potential difference across the membrane

Question 6

what muscle the energy in the glucose gradient exceed

Answer 6

the energy in the Na+ gradient times the energy in electrical gradient

Question 7

what is the chemical gradient for Na+

Answer 7

10 fold

-this gradient could sustain as much as a 10 fold gradient of another solute to which its flow is coupled

Question 8

what does secondary active transport generally do in mammal cells

Answer 8

most common strategy used by animal cells to move substrates against their electrochemical gradients

Question 9

why is membrane potential difference so important

Answer 9

1. influences the transport of many nutrients in and out of cells
2. a key driving force in the movement of salt across membranes and between organ based compartments
3. is an essential element in the signaling processes associated with coordinated movement of cells and organisms
4. is the basis of all cognitive processes

Question 10

how does membrane potential difference happen

Answer 10

1. presence of large gradients for K+ and Na+ across the plasma membrane
2. the relative permeability of the membrane to those ions

Question 11

what does the Nernst equation allow for

Answer 11

the calculation of the amount of electrical energy

Question 12

what happens when the chemical directed K+ gradient is larger than the electrical force

Answer 12

there will be a net flux of K+ from the cell