Nessa Carey

DNA --> mRNA --> proteins --> you understand life! Well, it was never that simple but now it's not even an accurate description of all the functions of DNA. Genes exist in binary "off or on" states. Wrong! Many genes effectively have dimmer switches that allow a continuous spectrum of activation from fully off to some maximum rate of expression. 98% of our DNA is "junk." Wrong! Only 2% codes for proteins but various parts of the rest are now understood to serve several functions, from acting show more as the above mentioned dimmer switches, to coding for types of RNA that serve functions other than being an intermediary in protein production, including suppressing cancerous changes in cells. Things that happened to your parents or even grandparents can affect your phenotype, e.g. how prone you are to obesity.

In other words, however complicated you thought molecular biology was twenty years ago, when people were hubristically saying, "we almost understand 'the cell' completely," it turns out it's way more complicated than that. The revolution described here bares a resemblance to that that occurred in physics at the turn of the 20th Century, where comments regarding physics being essentially complete turned out to be spectacularly wrong. What is this revolution? It's the understanding that the structure of DNA cannot be functionally reduced to a list of base-pairs. The Watson-Crick double-helix model of DNA isn't the whole story. If it was, all your autosomes (non-sex chromosomes) would be metres long and never fit inside a microscopic cell. The fact that chromosomes fold up into tight, tiny balls that sit roughly in the middle of each cell was known before the fact that they are made of DNA was. It turns out that this folding up has profound consequences beyond just allowing the molecules to fit in a confined space. So does where methyl groups are present on base pairs and how many are present. The same goes for histones. Ditto acetyl groups. Read this book if you want to know what these consequences are in such diverse contexts as aging, mental health, cancer, obesity and anorexia.

If you don't know what any of the above mentioned molecules are, don't worry; this book gives good, comprehensible explanations that I could easily follow from hazy memories of school chemistry and there is a glossary, in case you forget something. It's an incredibly useful few pages and yet it's often neglected in pop sci books.

There are other things I can strongly recommend about this book. It is well referenced, so if you're inclined to look up the technical details and verify what Nessa is saying, you can. Nessa is mostly presenting work that is not controvercial today, even though it is radical by standards of the end of last century. When she does talk about matters that are still murky - when there is still no consensus today - she tells you. She also isn't on a giant self-promotion exercise for her own theories, as many pop sci writers are. All of this makes her trust-worthy in my eyes, in stark contrast to many pop sci authors.

If you are at all interested in molecular biology, this book is worth your time. It's contents fascinated me. show less

98% of our DNA has until recently been considered "junk." That's the percentage that's not devoted to recipeing proteins, which for decades was supposed to be what DNA was all about. But the view of so-called junk DNA has been slowly changing. Better tools and procedures have allowed researchers to locate mutations implicated in rare genetic diseases, and many of these mutations turn out to be located in the "junk" areas. As clues mount, scientists can start connecting dots and developing show more theories regarding multitudes of previously unconsidered ways in which genetic errors can cause problems.

Ms. Carey's book does not make many generalizations about junk DNA's overall purposes might be. Instead she relates disparate tales of research results as relating to known genetic disorders. Her stories exemplify the strange, non-intuitive ways that genetic information can interact. It doesn't seem likely that science will soon have an orderly story to tell about how it all works.

Many of the interactions are actually epigenetic rather than genetic, meaning that they concern markers added to the the genetic code rather than the code itself. Epigenetic markings can be prompted by changes in the cell environment. Their purpose is to enable, amplify, damp down, or turn off individual genes. Their role and presence vastly complicates the whole genetic picture. Richard Dawkins's view of genes as simple, coherent actors seems increasingly naive.

This book is well and entertainingly written, but may be too technical for some readers. Something of a refresher course in cell biology might be advisable before giving this a go. show less

Turns out Lamarck was partially right after all. Gene expression can be turned on and off via a few molecular mechanisms that depend on a cell's environment. These mechanisms can be enabled or disabled from macro factors like stress (via corticosteroids) or micro factors like adjacent cells (this is how a zygote transforms into specialized cells during fetal development). Most surprising is that these epigenetic changes can be passed down through several generations.

After learning about how parents' and grandparents' experiences can have an effect on the present generation because of the affect on a person's genes, I became very interesting in learning more about this. The science behind the turning on or repressing of genes is called epigenetics.

I wanted to find out more and one of the books that I read on the subject is "The Epigenetics Revolution". It had stories like the lingering affects of the Danish Hunger Winter and other known events that can show more be tracked forward to find out the effects on later generations. It also had a lot more scientific explanations; so scientific that there were chemical diagrams included. I was expecting the book to be more about the written theory but understand a bit more about how the mechanisms of epigentics operate now.

It was good, but sometimes hard to grasp. show less