In the second experiment, bacteria are grown in a culture medium depleted of Na+. Under these conditions, when P3 is inactivated and a drug stimulates the activity of P1, the pH of the culture medium decreases unless a chelating agent (trapping Na+) is added to the culture medium.
Complete the following sentences. (2 attempts) From the second experiment, you conclude that in the presence of substrate S, the ___(A)___ results in the P1-dependent ____(B)____ of Na+ outside the bacteria. The Na+ ____(C)____ via P2, and this transport is coupled with H+ ___(D)___ leading to the formation of a proton motive force/Na+ gradient. The extracellular ___(E)___ re-enters the cell via P3 leading to ATP synthesis.
Options:
A: decarboxylation, carboxylation
B: export, import
C: re-enters, exits
D: export, import
E: H+, Na+