What do you know about DNA? What more can we learn from DNA?
As a biologist, I never cease to be amazed by living things. The hovering of a hummingbird; the brilliant, delicate petals of a rose; the drumming of a woodpecker on a tree trunk; the thousand-mile migration of monarch butterflies from North America to the central mountains of Mexico; the transformation of a caterpillar into a butterfly . . . these are just a few of the marvelous spectacles found in animals and plants of all shapes and sizes.
But there is one aspect of all living things that we frequently pass over or don’t even recognize. At the core of every living being is a molecule known most commonly by its acronym: DNA. You could say that DNA is the stuff of life. Contained in this paradoxically simple yet complex, odd yet beautiful molecule is the code that determines what every creature is composed of. All of life’s proteins—proteins of both structure and function—are coded in DNA.
This code is usually referred to as the genetic code. But what exactly is the genetic code?
DNA as Code
As it exists in all our cells, DNA is a string of four different subunits linked together chemically. Cellular DNA actually exists as two strands that run in opposite directions and then twist together, as if twisting a ladder around a central pole. That doesn’t sound very code-like, you may say. Well, perhaps, but I’m not finished. Recall that I mentioned four subunits above. These four subunits are usually abbreviated by the first letter of their chemical name, so I’ll just use A, G, C, and T.
DNA molecules can link together literally millions of these subunits. But in cellular DNA these strings of subunits do not exist in isolation. They are paired together with subunits of the other string, because DNA is double-stranded. An A always pairs with a T and a G always pairs with a C. So if you know the sequence of one strand, you will know the sequence of the other strand.
On top of all that, each “letter” of the code is like a letter of the English alphabet. The English alphabet uses twenty-six letters to make limitless words. A word can be made up of as few as one letter or as many as over a dozen letters. But in the genetic code, these chemical letters A, G, C, and T are grouped into “words” made up of only three letters. These three-letter words are referred to as codons. Sixty-one of the sixty-four possible three-letter codons code for one of the twenty amino acids found in living cells. The other three codons are “stop” messages.
This means that the sequence of the DNA letters determines the amino acid sequence of proteins. The sequence of amino acids in proteins is largely responsible for the three-dimensional shape of the protein, which determines its function in great part. So, encoded in the sequence of DNA molecules are the digital instructions to code for proteins, the workhorses of any cell.
We use letters to form words like DNA uses nucleotide subunits to form codons. Each codon codes for a specific amino acid. We use words to compose sentences. The sequence of codons forms a gene, and the sequence of amino acids forms proteins. We use sentences to form paragraphs, which are then grouped into articles or chapters of a book. Groups of genes and other DNA elements form chromosomes. When books and magazines are brought together, we call this a library. When chromosomes are assembled into the nucleus of a cell, we call this a genome.
You could represent the parallels in the following table:
|Words||=||Codons (amino acids)|
What I’m trying to demonstrate is that the genetic code is a language. We use linguistic words to describe what happens to DNA. DNA is transcribed into mRNA, which is like a dialect of DNA. The mRNA is then translated into protein, a totally different language.
This is not just a clever use of analogous terms. These linguistic terms accurately describe what is actually happening. The genetic code is an informational code or a language; it’s even in digital form.
So What Does It All Mean?
If you let your mind contemplate that for just a bit, a few important observations begin to emerge.
First, biology becomes the study of complicated and beautiful things that, at their very core, operate on the basis of a digital code. Second, this genetic code is revealed as a language that communicates within the cell, through proteins, and between cells. Third, our only other exposure to informational codes or language is humans and the machines we design.
Informational codes require preprogramming. In simpler terms, informational codes require a mind to create them, an intelligence that designs them. Even the sophisticated communication systems of whales, dolphins, and other mammals originate in a brain and are interpreted by a preprogramming in the brain. We have never observed nor would we even postulate a human language occurring through undirected chemical processes. As such, the DNA genetic code also requires intelligence for its original formulation. Once in place, it functions quite well.
Cells are living factories with modular construction, automatic assembly, information storage units, motorized delivery systems, power stations, scaffolding, and even a complete replication system. All of this in a system one thousand times smaller than our best smartphones!
Even contemplating the mind behind all of this incredible and beautiful design is awe-inspiring. This designing force would need to have existed before all life-forms as we know them. The language of DNA seems to be speaking of such a designer, a designer consistent with the God of the Bible.