Power, Sex, Suicide: Mitochondria and the Meaning of Life
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If it weren't for mitochondria, scientists argue, we'd all still be single-celled bacteria. Indeed, these tiny structures inside our cells are important beyond imagining. Without mitochondria, we would have no cell suicide, no sculpting of embryonic shape, no sexes, no menopause, no aging.
In this fascinating and thought-provoking book, Nick Lane brings together the latest research in this exciting field to show how our growing insight into mitochondria has shed light on how complex life evolved, why sex arose (why don't we just bud?), and why we age and die. These findings are of fundamental importance, both in understanding life on Earth, but also in controlling our own illnesses, and delaying our degeneration and death. Readers learn that two billion years ago, mitochondria were probably bacteria living independent lives and that their capture within larger cells was a turning point in the evolution of life, enabling the development of complex organisms. Lane describes how mitochondria have their own DNA and that its genes mutate much faster than those in the nucleus. This high mutation rate lies behind our aging and certain congenital diseases. The latest research suggests that mitochondria play a key role in degenerative diseases such as cancer. We also discover that mitochondrial DNA is passed down almost exclusively via the female line. That's why it has been used by some researchers to trace human ancestry daughter-to-mother, to "Mitochondrial Eve," giving us vital information about our evolutionary history.
Written by Nick Lane, a rising star in popular science, Power, Sex, Suicide is the first book for general readers on the nature and function of these tiny, yet fascinating structures.
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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