The point of taking on 50 Genetic Ideas You Really Need to Know (see my highly complimentary review of this primer by Mark Henderson) was to return to another of those ‘destinations’ that won’t leave me alone. I’ve tried to analyze why genetics attracts me. All I can suppose is that as one of those crux points of science and technology, one that sits at the root of humanity’s understanding of itself, the field of genetics will eventually toss me ideas or images or plots for my writing. To put it another way, I’m not interested in doing postgraduate studies in genetics, which is what is needed for proper understanding, but I do wish to explore key notions in readable books or on non-academic blogs. So the question is: has 50 Genetic Ideas provided a guide to further reading? What did I learn?
- I do now have a firmer grasp of some of the basics. For example, I struggled to relate chromosomes to genes, something Henderson resolves by describing chromosomes (on page 13) as ‘usually depicted as sticks that are pinched in the middle, but they actually take on this form only during cell division. For most of the time, they are long, loose strings, like fabric necklaces. Genes are like patches of colour woven into the design.’
- I knew about DNA’s helix of the letters A, T, C and G, but I’d failed to understand that triplets of those four letters, 64 of them in number (4 cubed equals 64, right?), code onto the twenty amino acids that make up the incredibly complex world of proteins that is us.
- There are 3 billion letters in our combined chromosomes. Only 1% to 2% code for proteins. The overwhelming majority are co-called ‘junk DNA’ – I had heard of this and had somehow learned that this is meant to be one way for nature to feature useful redundancy, but I was startled to learn from Henderson that recent discoveries suggest such DNA is not useless after all.
- Sequences of letters make up genes, which genetically determine or influence our physical characteristics. The 2001 publication of the human genome (I read an exciting book about it soon afterwards), which is simply a list of all such genes, unexpectedly tallied to only a fifth of the numbers expected. ‘At the time of writing, the latest count is about 21,500 – slightly more than the zebrafish, and slightly fewer than the mouse. There is little correlation between the biological complexity of an organism and its number of protein-coding genes.’ Wow!
- Henderson dedicates four chapters to demolishing both extremes of the nature (i.e. genetic determinism) versus nurture spectrum.
To my mind, I’ve learned quite a lot. Where to now? Let me find five or so of Henderson’s ‘ideas’ to pursue via books or articles, but in particular through active blogs.