Case Study 2 WwWL
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 positive charge. The electron transport chain that is part of the process of cellular respiration powers carrier protein “pumps” which actively transport H+ ions (single protons) from the mitochondrial matrix across the inner membrane to the intermembrane space. As a result, the intermembrane space contains many protons, and therefore this is an area of relatively great positive charge. In contrast, the mitochondrial matrix contains few protons, and therefore it has a less positive charge. It is important to note that although the mitochondrial matrix does contain some protons --and as a consequence, has some positive charge-- it is much less positive than the intermembrane space, making it relatively negative as compared to the intermembrane space. This difference in charge creates a potential difference across the inner membrane of the mitochondria. This voltage draws the protons existing in the intermembrane space towards the mitochondrial matrix on the other side of the inner membrane. However, the membrane is impermeable to the protons, and therefore they must travel through a special protein called the ATP synthase. As the protons pass through the synthase towards the relatively negative mitochondrial matrix, they spin a special
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 positive charge. The electron transport chain that is part of the process of cellular respiration powers carrier protein “pumps” which actively transport H+ ions (single protons) from the mitochondrial matrix across the inner membrane to the intermembrane space. As a result, the intermembrane space contains many protons, and therefore this is an area of relatively great positive charge. In contrast, the mitochondrial matrix contains few protons, and therefore it has a less positive charge. It is important to note that although the mitochondrial matrix does contain some protons --and as a consequence, has some positive charge-- it is much less positive than the intermembrane space, making it relatively negative as compared to the intermembrane space. This difference in charge creates a potential difference across the inner membrane of the mitochondria. This voltage draws the protons existing in the intermembrane space towards the mitochondrial matrix on the other side of the inner membrane. However, the membrane is impermeable to the protons, and therefore they must travel through a special protein called the ATP synthase. As the protons pass through the synthase towards the relatively negative mitochondrial matrix, they spin a special