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The Gene: An Intimate History

by Siddhartha Mukherjee

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David said: " "For Darwin’s theory to work, heredity had to possess constancy and inconstancy, stability and mutation."

"Against this backdrop, the US Supreme Court took scarcely any time to reach its decision on Buck v. Bell. On May 2, 1927, a few weeks before Car "For Darwin’s theory to work, heredity had to possess constancy and inconstancy, stability and mutation."

"Against this backdrop, the US Supreme Court took scarcely any time to reach its decision on Buck v. Bell. On May 2, 1927, a few weeks before Carrie Buck’s twenty-first birthday, the Supreme Court handed down its verdict. Writing the 8–1 majority opinion, Oliver Wendell Holmes Jr. reasoned, “It is better for all the world, if instead of waiting to execute degenerate offspring for crime, or to let them starve for their imbecility, society can prevent those who are manifestly unfit from continuing their kind. The principle that sustains compulsory vaccination is broad enough to cover cutting the Fallopian tubes.”

“Seek simplicity, but distrust it,” Alfred North Whitehead,

"It is the form of hemoglobin, then, that permits its function. The physical structure of the molecule enables its chemical nature, the chemical nature enables its physiological function, and its physiology ultimately permits its biological activity. The complex workings of living beings can be perceived in terms of these layers: physics enabling chemistry, and chemistry enabling physiology."

"a gene “acts” by encoding information to build a protein, and the protein actualizes the form or function of the organism."

"What is a gene, then? When Mendel discovered the “gene” in 1865, he knew it only as an abstract phenomenon: a discrete determinant, transmitted intact across generations, that specified a single visible property or phenotype, such as flower color or seed texture in peas. Morgan and Muller deepened this understanding by demonstrating that genes were physical—material—structures carried on chromosomes. Avery advanced this understanding of genes by identifying the chemical form of that material: genetic information was carried in DNA. Watson, Crick, Wilkins, and Franklin solved its molecular structure as a double helix, with two paired, complementary strands. In the 1930s, Beadle and Tatum solved the mechanism of gene action by discovering that a gene “worked” by specifying the structure of a protein. Brenner and Jacob identified a messenger intermediate—an RNA copy—that is required for the translation of genetic information into a protein. Monod and Jacob added to the dynamic conception of genes by demonstrating that genes can be turned on and off by increasing or decreasing this RNA message, using regulatory switches appended to each gene. The comprehensive sequencing of the worm genome extended and modified these insights on the concept of a gene. A gene specifies a function in an organism, yes—but a single gene can specify more than a single function. A gene need not provide instructions to build a protein: it can be used to encode RNA alone, and no proteins. It need not be a contiguous piece of DNA: it can be split into parts. It has regulatory sequences appended to it, but these sequences need not be immediately adjacent to a gene."

"It accommodates enough variation to make each one of us distinct, yet enough consistency to make each member of our species profoundly different from chimpanzees and bonobos, whose genomes are 96 percent identical to ours."

"Of all the sciences, biology is the most lawless; there are few rules to begin with, and even fewer rules that are universal. Living beings must, of course, obey the fundamental rules of physics and chemistry, but life often exists on the margins and interstices of these laws, bending them to their near-breaking limit. The universe seeks equilibriums; it prefers to disperse energy, disrupt organization, and maximize chaos. Life is designed to combat these forces. We slow down reactions, concentrate matter, and organize chemicals into compartments; we sort laundry on Wednesdays. 'It sometimes seems as if curbing entropy is our quixotic purpose in the universe,' James Gleick wrote. We live in the loopholes of natural laws, seeking extensions, exceptions, and excuses. The laws of nature still mark the outer boundaries of permissibility -- but life, in all its idiosyncratic, mad weirdness, flourishes by reading between the lines. Even the elephant cannot violate the law of thermodynamics -- although its trunk, surely, must rank as one of the most peculiar means of moving matter using energy."

"A cell without the capacity to selectively silence parts of its genome devolves into Funes the Memorious (or, as in the story, Funes the Incapacitated). The genome contains the memory to build every cell in every tissue in every organism -- memory so overwhelmingly profuse and diverse that a cell devoid of a system of selective repression and reactivation would become overwhelmed by it. As with Funes, the capacity to use any memory functionally depends, paradoxically, on the ability to silence memory. Perhaps an epigenetic system exists to allow the genome to function." ...more "

Mar 02, 2017 09:03PM · see review