My father recently brought to my attention an article about a “second DNA code” discovered hiding within DNA:
DNA contains about 3 billion bases, more than 99 percent of which are the same in all human beings. “The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences,” according to the National Institutes of Health.
For instance, the genetic code uses a 64-letter alphabet called codons. The team found that some codons, which they refer to as duons, can have two meanings. One of the meanings relates to protein sequence, while the other relates to gene control.
Forbes and Geek.com both have good “easy there big fella” articles if you’re interested in why this isn’t necessarily news, but this is a great opportunity to talk about what we do know about DNA and what you as a probably-not-genetics-researcher should know. I’m going to assume you’ve at least heard of DNA, but not much more.
Every cell in your body typically has 23chromosomes. Each of these chromosomes is made of a lot of DNA (each strand is between 2 and 3 meters long), coiled up in some pretty crazy ways, but at the most basic level, you’re looking at that classic “double helix” coil. Each strand of DNA has a bunch of genes on it with a bunch of stuff in between – think of it like a really long book with some chapters in English and some in Finnish. You page through it looking for English words; when you see some, you start reading, and you get some ideas out of it.
The English chapters are the protein-coding genes, which use the 64-codon alphabet the quote above is talking about. Some of the Finnish chapters, on the other hand, are actually functioning to determine how frequently you read a particular English chapter. These are transcription factors.
Here, of course, is where my analogy breaks down; a protein binds to the transcription factor site and says HEY RNA POLYMERASE COME READ THIS ONE, and the RNA polymerase comes over and makes a protein out of the gene the protein was yelling about. If the protein made is another one that can bind to another transcription factor site, you can get positive feedback loops, and you get more and more of a certain kind of protein (until there’s “enough”, and you start getting other proteins that bind and say NOPE NO GENE HERE I DON’T KNOW WHAT YOU’RE TALKING ABOUT, and then that protein’s levels go down for a while).
So: chromosomes are made of DNA, DNA has genes and other stuff, that other stuff can be used, among other things, to tell the cell which genes to read and how often. DNA isn’t just a recipe book, it’s a meal plan and timer.
The research I’m doing, which is related, has to do with the fact that sometimes the same gene can make a bunch of different proteins, because sometimes the cell decides it doesn’t really like a particular part of a gene today, so it throws part of it away. That means you’re missing some codons (that 64-letter alphabet again), and so the resulting protein is actually measurably different. Which is AWESOME.