Block 2 Lecture 22 Flashcards
what is the source of energy in secondary active transport
the potential energy available in the transmembrane gradient of one or more other solutes
what is coupled transport
the downhill movement of one substrate serving to drive the uphill movement of another. coupled gradients are in opposite directions
what is the most commonly used solute gradient for secondary active transport
the inwardly directed Na+ gradient
what is the Na-D glucose cotransport (SGLTs)
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
what is the driving force for SGLTs
the chemical gradient for Na+ and the electrical potential difference across the membrane
what muscle the energy in the glucose gradient exceed
the energy in the Na+ gradient times the energy in electrical gradient
what is the chemical gradient for Na+
10 fold
-this gradient could sustain as much as a 10 fold gradient of another solute to which its flow is coupled
what does secondary active transport generally do in mammal cells
most common strategy used by animal cells to move substrates against their electrochemical gradients
why is membrane potential difference so important
- influences the transport of many nutrients in and out of cells
- a key driving force in the movement of salt across membranes and between organ based compartments
- is an essential element in the signaling processes associated with coordinated movement of cells and organisms
- is the basis of all cognitive processes
how does membrane potential difference happen
- presence of large gradients for K+ and Na+ across the plasma membrane
- the relative permeability of the membrane to those ions
what does the Nernst equation allow for
the calculation of the amount of electrical energy
what happens when the chemical directed K+ gradient is larger than the electrical force
there will be a net flux of K+ from the cell
