Discoveries sometimes take the wind out of our sails, like when scientists figured out that humans aren’t quite as complicated as previously thought – at least in terms of the number of genes a typical human body expresses. On the other hand, there are moments when our understanding of gene process opens new directions to explore, such as the fact that we know less, rather than more, about gene function. Period. That’s exciting. Lots of fictional avenues to wander down.
The human genome is of particular interest, especially if you enjoy writing stories that manipulate the physiology of the species.
The word genome refers to the hereditary information that genetically characterizes a human (think of a blueprint). This data is encoded in DNA as sets of 23 chromosome pairs (remember you get half the set from mom and the other half from dad). Twenty-two of these pairs are autosomal chromosomes, while the remaining pair is sex-determining.
Because every new generation of people is born from the admixture of chromosome pairs, the introduction of new genetic material happens rapidly – sex cells are important. Look at any family group with children deriving from the same two parents and you can easily see how the same parental chromosomes produce a vast variety of expressions.
The complete genetic sequence of the human genome includes both genes (2%) and non-coding sequences of DNA (98%). So, there you are – we’re made mostly of junk DNA. While the “junk” doesn’t promote active protein sequencing, it is useful and important – we think. We’re still figuring out how this stuff all works.
Back in the day, scientists used to talk about mapping the entire human genome and how cool it would be to know the entire parts list of the human species (yes, most of them are quite dorky). They talked about the idea, dreamed of marking down three billion base pairs of CGTAs, and then suddenly… it was happening. Computers made the process fast.
The Human Genome Project produced a referenced sequence of the human genome. Today, the results are used worldwide in all the fields of biomedical sciences. It turns out that the human genome occupies just over 3 billion DNA base pairs. What does that mean in plain terms? Each person contains an estimated 20,000 to 25,000 protein-coding genes. So when you mix it up with a partner and produce offspring – voila, instant variation. Incidentally, different is good, especially in biological terms. What is most interesting about this, is that the number of 20-25K is far fewer than previously estimated. In fact, in good academic form, medical schools have taught how humans were believed to have at least a 100K genes. Oops. Whoever pulled that number out of the ether is now blushing. Since we’ve actually counted, the textbooks have been updated. Again.
In the years since this achievement, the genomes of many species have been sourced. This provides great value in understanding how different and similar are organisms, and their connectedness over time. Knowing the human genome helps in resolving genetic disease, but gene mapping is only one aspect of what makes a person. We certainly can’t exclude the power of environment, life choices, and who knows what else.
If you’d like to explore this topic some more without getting bogged down in big words and information that could choke an elephant, try these sources:
Not only is this stuff just interesting to know about – for writers there are endless applications. It doesn’t take an advanced degree to understand or utilize the process, just a basic understanding of biology. There are a ton of resources out there and so much fascinating information to explore – what are you still doing here? Let’s do some gene manipulation!