Reading5_vitalforce - The Vital Force Proton Power and the...

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The Vital Force: Proton Power and the Origins of Life An Introduction to the topic, From Lane, Nick. 2005. Power, Sex, Suicide: Mitochondria and the Meaning of Life . Oxford University Press, Oxford. Excerpts from Part 2: The Vital Force: Proton Power and the Origins of Life, pages 66-93. “Energy and life go hand in hand. If you stop breathing, you will not be able to generate the energy you need for staying alive and you’ll be dead in a few minutes. Keep breathing. Now the oxygen in your breath is being transported to virtually every one of the 15 trillion cells in your body, where it is used to burn glucose in cellular respiration. You are a fantastically energetic machine. Gram per gram, even when sitting comfortably, you are converting 10 000 times more energy that the sun every second. This sounds improbable, to put it mildly, so let’s consider the numbers. The sun’s luminosity is about 4 x 10 26 watts and its total mass is 2 x 10 30 kg. Over its projected lifetime, about 10 billion years, each gram of solar material will produce about 60 million kilojoules of energy. The generation of this energy is not explosive, however, but slow and steady, providing a uniform and long-lived rate of energy production. At any one moment, only a small proportion of the sun’s vast mass is involved in nuclear fusions, and these reactions take place only in the dense core. This is why the sun can burn for so long. If you divide the luminosity of the sun by its mass, each gram of solar mass yields about 0.0002 milliwatts of energy, which is 0.0000002 joules of energy per gram per second (0.2 μ J/g/sec). Now let’s assume that you weight 70 kg, and if you are anything like me you will eat about 12 600 kilojoules (about 3000 calories [sic]) per day. Converting this amount of energy (into heat or work or fat deposits) averages 2 millijoules per gram per second (2 mJ/g/sec) or about 2 milliwatts per gram – a factor of 10 000 greater than the sun. Some energetic bacteria, such as Azotobacter , generate as much as 10 joules per gram per second, outperforming the sun by a factor of 50 million. At the microscopic level of cells, all life is animated, even the apparently sessile plants, fungi, and bacteria. Cells whirr along, machine-like in the way that they channel energy into particular tasks, whether these are locomotion, replication, constructing cellular materials, or pumping molecules in and out of the cell. Like machines, cells are full of moving parts, and to move they need energy. . . . [Peter Mitchell] put forward a radical new hypothesis in Nature in 1961 . . . He proposed that respiration in cells worked by chemiosmotic coupling , by which term he meant a chemical reaction that could drive an osmotic gradient, or vice versa. Osmosis is a familiar term from schooldays, even if we can’t quite remember what it means. It usually means the flow of water across a membrane from a less concentrated to a more concentrated solution, but Mitchell, characteristically, didn’t mean it in that sense at all. By ‘chemiosmosis’ we might imagine that he
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This note was uploaded on 03/08/2011 for the course BIS 2A taught by Professor Grossberg during the Fall '08 term at UC Davis.

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Reading5_vitalforce - The Vital Force Proton Power and the...

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