Tag Archives: DNA

The Gene – An Intimate History (1/2)

In January I finished reading and wrote about The Emperor of All Maladies by Siddhartha Mukherjee. I was bemused that the history of cancer could be so captivating, all due to Mukherjee’s story telling prowess and facility with language. I immediately wanted to read more by him, and last night completed The Gene – An Intimate History.

Reading this book was no small feat! Night reading was difficult as my mind tended to wander or my eyes would droop into tiredness. I had no choice but to make this purely a the genedaytime read, meaning it took awhile to make my way through the 495 pages of text. Mukherjee’s writing sparked many questions and points of interest, as the sticky tabs attest. At one point I grabbed the nearest piece of paper, a page from the Sunday Times with sufficient white space for me to jot down my thoughts after reading pages 274-275, which is one of several times that eugenics and newgenics are discussed.

My response whilst reading those pages: If we are all alike we lose the beauty of our unique human differences because often a disease in one area yields a strength in another. That variety of strengths is what creates the range of thoughts, actions, and ideas without which we become more mono-thinking, mono-acting; we give up potential creative approaches and solutions to obstacles that life presents. “Uber-normalcy” yields inability to sustain life when, as will happen, an abnormality occurs.

Turns out, Mukherjee feels similarly. As he went on to state on the next page, “What if ‘disease-causing’ gene variants were also genius enabling?” To a certain degree, this theme percolates throughout the book as scientists uncover the foundations of genes, heredity, DNA and their inner related worlds, and discover (an ongoing process) ways of meddling in that soup. To be sure, sometimes the meddling is phenomenally beneficial, such as highly targeted approaches to cancer care. But the ability to meddle with our humanity opens up numerous safety, philosophical and ethical questions to which there are no easy or quick answers. Taken as a whole, this is a book about science, philosophy, ethics, social science, history, medicine, disease, and people.

I have gotten ahead of myself! Let’s back up to page 61, where I chuckled at chicken…was merely an egg’s way of making a better egg. This was the conclusion of Hugo de Vries, a Dutch botanist turned geneticist. de Vries built upon the work of Mendel and is credited with using the word mutants (change) to describe variations in plant life. From there he postulated that “these mutants had to be the missing pieces in Darwin’s puzzle.” And from there it became apparent that “natural selection was not operating on organisms but on their units of heredity.” Hence the italicized quote at the start of this paragraph.

Parts of this book were like biology and vocabulary lessons. (I was once exposed to some of this in high school.) The interplay of natural selection and evolution as they relate to genetics results in the words genotype, “an organism’s composition…[referring] to one gene, a configuration of genes, or even an entire genome” and phenotype, “an organism’s physical or biological attributes and characteristics–the color of an eye, the shape of a wing, or resistance to hot or cold temperatures.”

Along the lines of more basic biology and chemistry, how often do any of us stop to remember that sugars provide energy, fats store the energy, and proteins enable the chemical reactions that manage the process.

With the contemplation of the interplay of nature (genes) and nurture (environment), this led to some of the early stepping stones delineated by Mukherjee (p 107).

  • a genotype determines a phenotype
  • genotype + environment = phenotype
  • genotype + environment + triggers chance = phenotype

Slight digression – as a yoga teacher who has been known to say “let your breath be your guide” and “move with your breath,” I enjoyed the visual that came from an early chapter about the “gene molecule.” Mukherjee writes “Cells depend on chemical reactions to live: during respiration, for instance, sugar combines chemically with oxygen to make carbon dioxide and energy. None of these reactions occurs spontaneously (if they did, our bodies would be constantly ablaze with the smell of flambé sugar).” 

As the story of the gene unfolds, Mukherjee paints a picture that perfectly clarified for me the process of trying to understand DNA. He explains that

Chemists generally piece together the structure of a molecule by breaking the molecule down into smaller and smaller parts, like puzzle pieces, and then assembling the structure from the constituents. But DNA, broken into pieces, degenerates into a garble of four bases–A, D, G, and T. You cannot read a book by dissolving all of its words into alphabets. With DNA, as with words, the sequence carries the meaning. Dissolve DNA into its constituent bases, and it turns into a primordial four-letter alphabet soup. (p 216)

This post covered a little less than half of the sticky tabs stuck throughout the book as I marked pages to return for further thought. As most of the remaining tabs deal with a particular interest of mine, I will save them for a second post.