Case Study 2 WwWL

2386 Words Mar 9th, 2015 10 Pages
Case Study II -- Wrestling with Weight Loss: The Dangers of a Weight-Loss Drug
Part I
1. What do you know about the mitochondria?
The main function of the mitochondria is to convert fuel into a form of energy the cell can use. Specifically, the mitochondria is where pyruvate --derived from glucose-- is converted into ATP (Adenosine triphosphate) through cellular respiration. Cellular respiration involves four stages: glycolysis, the grooming phase, the citric acid cycle, and oxidative phosphorylation. The final two stages listed occur in the mitochondria.
Part II
2. What are the consequences of a proton gradient and how could a gradient be used in the mitochondrion? List all the possibilities that come to mind.
Protons have a strong
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b. To the amount of ATP produced by the mitochondria?
The lack of a proton gradient would mean that protons would no longer diffuse through the ATP synthase, as there is no difference in charge or concentration which would cause them to do so. When working normally, as protons pass through the synthase, they lose some energy, which is then used to bond ADP with Pi and form ATP. No proton gradient would mean no movement of protons through the synthase, and therefore ADP would not get the energy it requires to form ATP. Production of ATP in the mitochondria would greatly decrease, as this process (called oxidative phosphorylation) is responsible for 90% of ATP production. Substrate-level phosphorylation in the citric acid cycle would continue to produce ATP, but the overall production by the mitochondria would be only 10% of normal as oxidative phosphorylation stops.
c. To the energy released in the movement of the protons?
The movement of protons would no longer be controlled by the carrier protein embedded within the inner membrane of the mitochondria. Normally, the ATP synthase is able to use the potential energy contained in the protons passing through it to produce ATP, but as was explained in the previous question, protons would no longer be passing through the synthase. Uncontrolled movement of this kind would mean any energy release would be uncontrolled as well, and therefore

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