We saw that the population harvested 5 min post feeding contains proton pumps as opposed to the populations harvested 30 sec or 10 min post feeding.

Do these findings support any of the previously described hypotheses?

(Choose between likely and less likely)
 

Hypothesis B.The food vacuole membrane contains several proton pumps that allow the acidification of the food vacuole, once it has been formed. However, these proteins undergo proteolysis with time at low pH (between 7-10 minutes, as evident by Fig 1) . As the number of active pumps decreases, the pH within the food vacuole gradually increases.

Hypothesis C.The food vacuole undergoes fusion with lysosomes shortly after it is formed. The membranes of these lysosomes contain proton pumps, which now transport protons into the enlarged food vacuole.This explains the initial decrease in the pH. As migration continues and digestion is completed, the lysosome membranes containing the proton pumps are pinched off the vacuole, allowing the pH to increase.

B. These findings support the hypothesis of rapid degradation of proton pumps present in the membrane of the food vacuoles
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

According to both theories we expect the 5 min population to have proton pumps and the 10 min population to have less or no proton pumps. The difference between the two theories lies in the 30 sec population. Food vacuoles are incapable of protein synthesis. Therefore, the early food vacuoles should already contain the proton pumps according to the theory of rapid degradation of proton pumps present in the membrane of the food vacuoles (hypothesis B).  On the other hand, according to the fusion theory (hypothesis C), the proton pumps are imported to the food vacuole at a later stage following fusion with the lysosyme. We have previously noticed that the size of an early (30 sec) food vacuole is smaller than the size of the later (5 min) food vacuole and of the same size as the latest food vacuole (10 min). These findings support the fusion theory, but they do not prove it beyond any doubt. Continue