How to think about… Genes | Tech News
How does a mere 20,000 genes make a unique human? Even with a total rethink of how genes work we are struggling to grasp the intricacies of DNA
WHETHER they are humans or pea plants, the way living organisms look and behave is intimately connected with their genes. But ideas of genes and their workings have evolved hugely in the century since the word was coined.
In essence it is simple. “A gene is the stretch of DNA letters that encodes individual functional units or proteins,” says Stacey Gabriel of the Broad Institute in Cambridge, Massachusetts. Within our cells, double-stranded DNA is continually unzipped and transcribed into single-stranded RNA, which performs cell functions itself or can be used as a template to assemble the proteins that make us what we are.
As such, genes are basic, universal units of heredity. You generally have two copies of each, one from your mother and one from your father. Each gene has different versions that vary slightly at the molecular level, generating different outward effects – brown or blue eyes, for example.
We long thought there must be one gene for each outward characteristic, but that belief hasn’t stood the test of time. The Human Genome Project, completed in 2003, revealed that genes account for just 1 per cent of our DNA; the rest is “junk”. We have only 20,000 genes in total – far too few for the one gene, one function idea.
It turns out that genes do different things depending on factors like when and where they are expressed. “Genes can be alternatively spliced, which …