Consider a uniport system where a carrier protein transports an uncharged substa
ID: 499598 • Letter: C
Question
Consider a uniport system where a carrier protein transports an uncharged substance A across a cell membrane. Suppose that at a certain ratio of [A]_inside to [A]_outside, the Delta G for the transport of substance A inside from outside the cell to the inside A_outside rightarrow A_inside, is -10.3 kJ/mol at 25 degree C. What is the ratio of the concentration of substance A inside the cell to the concentration outside? Choose the true statement about the transport of A under the conditions described above. Increasing [A]_outside will cause Delta G for movement of A_outside to A_inside to become a smaller negative number. Decreasing the concentration of the uniport protein in the membrane will cause Delta G to become a larger negative number. Since Delta G is negative, the ratio [A]_inside/[A]_outside must be greater than one. Movement of A_outside to A_inside will be spontaneous.Explanation / Answer
1)
T = 25 oC = 298 K
use:
G = - R*T*ln Kc
G = - R*T*ln {[Ainside]/[Aoutside]}
-10300 J/mol = -8.314*298*ln {[Ainside]/[Aoutside]}
ln {[Ainside]/[Aoutside]} = 4.157
{[Ainside]/[Aoutside]} = 63.9
Answer: 63.0
2)
G = - R*T*ln {[Ainside]/[Aoutside]}
since G is negative, [Ainside]/[Aoutside]} must be greater than one