NonCodingDNA

If you’ve found your way to this website it’s likely that you have some background in biology, genetics, or a related field. However if some of the jargon you encounter on this site or in the field of genetics is new to you, don’t be discouraged. Although scientists sometimes give complex names to things, most of the principles that describe the natural world are easy to understand.

Before we begin discussing the main topic of this website, noncoding DNA, it might be beneficial to talk about some basic ideas. First, let’s talk about this thing called DNA. DNA stands for deoxyribonucleic acid. DNA holds most, if not all, of the instructions that guide any biologic organism. So whether you’re a bacteria, a pine tree, or a human, DNA is running the show. The total amount of DNA that programs an organism is called its genome. It’s not completely understood how DNA tells some of the cells in your body to become brain cells and others to become liver cells. We do know that without DNA a cell cannot successfully reproduce or pass on what it has “learned” about an environment.

The genome can be divided into two main sections, the coding and noncoding (what is called junk DNA today) portions. The coding section of the genome is generally what we talk about when we refer to genes. Genes take part in a process where DNA is converted to a form of ribonucleic acid (RNA), which is then converted to protein. This has been called “the central dogma,” although somewhat incorrectly.

It was believed that genes performed most of the important biological functions, and that more complex organisms (like us) would have many more genes than other species. In fact, that’s not what we’ve discovered. Humans have the same number of genes as mice and puffer fish and have fewer genes than several plant species.

Are we really less complex than rice?

Genes make up only 2% of the genome, leaving over 98% of our genome which has been labled as “junk” (i.e. noncoding DNA). But, what if the junk isn’t junk?

The scientific paper at the hub of this website suggests that while genes are important, there are known (and probably many unknown) elements in noncoding DNA that are essential to all organisms. In fact, it is likely that these elements are what are controlling organismal complexty. If we examine genomes from multiple species and look at how much noncoding DNA they have, we find that the amount of noncoding DNA per genome correlates very well with our current descriptions of biological complexity. That is, bacteria don’t have very much noncoding DNA, protozoans have more than bacteria, fungus have more than protozoans, and humans have the most.

So the take home message appears to be:

The greater the relative amount of noncoding DNA an organism has the more complex it is.

A correlation doesn’t mean very much without data to support it.

An increasing body of evidence is showing that noncoding DNA sequences play instrumental roles in everything from cell division to leaf development in plants. Several human diseases have now been associated with “errors” in noncoding sequences. Additionally, the role of noncoding RNAs – one of the products of noncoding DNA – seems to be incredibly substantial.

If all of this is true why do we still think there’s junk in the genome?

Until recently it was quite reasonable to think that there were vast amounts of “junk” DNA in the genome. Genes and their products (proteins) are big, and easy to study. Therefore, they have garnered almost all of the scientific attention. The technology to study noncoding sequences is just now coming of age, and is consequently revealing all their biologic roles.

What’s next?

Continuing research on noncoding RNA and DNA sequences is likely to reveal how complex our genetic programming really is. We’ll have to see how deep the genomic rabbit hole really goes…