You are studying ion channels and have set up model lipid vesicles containing the three following transporters: 1. a Na+ /H+ antiporter driven by the Na+ concentration gradient.
2. The common 3Na+ /2K+ pump.
3. K+ leak channels. The experiments are designed such that all three transporters are oriented in the model lipid bilayers in the same direction they would be in the plasma membrane of a cell and that concentration gradients in vitro mimic the concentration gradients experienced by cells (e. g., the extracellular Na+ concentration is similar to the concentration outside of the vesicle whereas the concentration in the lumen of the model vesicles is similar to intracellular Na+ levels).

Required:
a. Draw the arrangement and ion flow of the three types of transporters in the model membranes.
b. What do you predict will happen to the pH of the vesicle lumen if you treat the model membranes with the drug oubain that impairs function of the 3Na+/2K+ pump? Briefly explain your answer in terms of what happens with each transporter.

Answer and Explanation:

a) you will find the arrangement and ion flow of the three types of transporters in the model membranes in the attached files.

Under normal conditions, the cell interior has a lower pH than the exterior. The K+ concentration is higher in the interior, while the Na+ concentration is higher in the cell exterior. The interior of the cell is always more electronegative than the cell exterior.

b)

The drug ouabain inhibits the pump. It impedes the Na+ exit and the K+ entrance. It occurs a sharp increase in the Na+ intracellular concentration, which influences the Na+ /H+ antiporter that changes the ions´ direction, taking out Na+ and bringing in H+ to compensate the intracellular Na+ excess. There is also a decrease in the leak channel function, which does not allow K+ to leave the cell.

Whenever the pump is inhibited, there is an increase in the intracellular pH, because Na+ concentration increases in the interior.

"griffith's experiment discovering the "transforming principle" in pneumococcus bacteria. griffith's experiment, reported in 1928 by frederick griffith, was the first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation." - griffith's experiment.

prism b but im not for sure