Chapter 1. Cellbots II

1.1 Cellbots II

With the problem of the malfunctioning mitochondria resolved, you and your team are disheartened to find that the Cellbots are still unable to produce ATP on their own and do not thrive unless they are supplied with exogenous glucose. The Cellbots were designed with chloroplasts so they would be able to synthesize their own carbohydrate energy source. Surmising that there may be a problem with the photosynthetic manufacture of carbohydrate, you and your team now turn your attention to the Cellbot chloroplasts.

The chloroplasts appear normal in number and normal morphologically at the ultrastructure level. Biochemically, all of the enzymes, pigments, and cofactors, normally found in plant chloroplasts are present in normal quantities in those of the Cellbots. Yet, even under optimum conditions of illumination, carbohydrate production is practically nil. Your team finds that the Cellbot chloroplasts are different from normal chloroplasts in two ways. First, the pH in the stroma is the same as the pH in the thylakoid lumens. Second, ATP production in isolated Cellbot chloroplasts is much lower than anticipated. The BP scientists are not concerned about his when you told them because they are under the impression that ATP production is only important for mitochondria. Both of these findings are cause for concern because _____ .

1.2 Similar but not Identical

Your team member who cracked the mitochondria case wide open suggests taking the same approach to the current problem. You agree and she performed a gene expression analysis on isolated chloroplasts. Déjà vu all over again- this time, a leaky hydrogen ion channel gene similar but not identical to the one expressed in the Cellbot mitochondria, is discovered in the chloroplasts. And this hydrogen ion channel is present as an integral membrane protein in the chloroplast, this time in the thylakoid membrane.

1.3 Renegade Hydrogen Ion Channel

To test the hypothesis that the lack of ATP production in the chloroplast is due to the presence of the renegade hydrogen ion channel, you suggest to the BP team of scientists that they isolate chloroplasts from Cellbots and test them under experimental conditions, including in the presence of the new inhibitor designed specifically to block the function of the ectopic chloroplast hydrogen ion channel protein.