Power, Sex, Suicide: Mitochondria and the Meaning of Life

Power, Sex, Suicide: Mitochondria and the Meaning of Life

Nick Lane

Language: English

Pages: 368

ISBN: 0199205647

Format: PDF / Kindle (mobi) / ePub





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Mitchell was interested in vectorial metabolism, which is to say, reactions that have a direction in space as well as time. The key to bacterial transport systems, for Mitchell, lay in the outer membrane of the bacterial cell. This was plainly not just an inert physical barrier, as all living cells require a continuous and selective exchange of materials across this barrier. At the least, food must be taken up and waste products removed. The membrane acts as a semipermeable barrier, restricting

biology. Even equipped with this vocabulary, some sections may still seem challenging. I believe it’s worth the effort, for the fascination of science, and the thrill of dawning comprehension, comes from wrestling with the questions whose answers are unclear, yet touch upon the meaning of life. When dealing with events that happened in the remote past, perhaps billions of years ago, it is rarely possible to ﬁnd deﬁnitive answers. Nonetheless, it is possible to use what we know, or think we know,

such as starvation or suffocation, or perhaps a metabolic shortage of raw materials, then the speed of respiration reﬂects the supply rather than the demand. In both cases, however, the overall speed of respiration is reﬂected in the speed that electrons ﬂow down the respiratory chain. If electrons ﬂow quickly, glucose and oxygen are consumed quickly, and by deﬁnition, respiration is fast. Now, after this little detour, we can return to the point. There is a third factor that causes respiration

black plague, rats still symbolize squalor and ﬁlth, but we are also indebted to them: in the laboratory, their clean-living cousins have helped rewrite the medical texts, serving as models of human diseases and (in that archaic turn of phrase) as guinea pigs for many new treatments. Rats are useful laboratory animals because they are like us in many ways—they, too, are mammals, with the same organs, the same layout and basic functionality, the same senses, even sensibilities—they share a lively

between the resting value of mass2/3 or mass3/4 (whichever value is correct) and the value for muscle, of mass to the power of 1. It doesn’t quite reach an exponent of 1 because the organs still contribute to the metabolic rate, and their exponent is lower. So the capillary density reﬂects tissue demand. Because the network as a whole adjusts to tissue demands, the capillary density does actually correlate with metabolic rate—tissues that don’t need a lot of oxygen are supplied with relatively

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