The Case for a Creator - Lee Strobel [120]
“Let’s talk about DNA, then,” I said. “You’ve written that there’s a ‘DNA-to-design argument.’ What do you mean by that?”
Meyer removed a pair of gold-rimmed glasses from his shirt pocket and put them on as he began to give his answer. “Very simply,” he said, “I mean that the origin of information in DNA—which is necessary for life to begin—is best explained by an intelligent cause rather than any of the types of naturalistic causes that scientists typically use to explain biological phenomena.”
“When you talk about ‘information’ in DNA, what exactly do you mean?” I asked.
“We know from our experience that we can convey information with a twenty-six-letter alphabet, or twenty-two, or thirty—or even just two characters, like the zeros and ones used in the binary code in computers. One of the most extraordinary discoveries of the twentieth century was that DNA actually stores information—the detailed instructions for assembling proteins—in the form of a four-character digital code.
“The characters happen to be chemicals called adenine, guanine, cytosine, and thymine. Scientists represent them with the letters A, G, C, and T, and that’s appropriate because they function as alphabetic characters in the genetic text. Properly arranging those four ‘bases,’ as they’re called, will instruct the cell to build different sequences of amino acids, which are the building blocks of proteins. Different arrangements of characters yields different sequences of amino acids.”
With that, Meyer decided to show me an illustration he often uses with college students. Reaching over to a desk drawer, he took out several oversized plastic snap-lock beads of the sort that young children play with. “It says on the box that these are for kids ages two to four, so this is advanced chemistry,” he joked.
He held up orange, green, blue, red, and purple beads of different shapes. “These represent the structure of a protein. Essentially, a protein is a long linear array of amino acids,” he said, snapping the beads together in a line. “Because of the forces between the amino acids, the proteins fold into very particular three-dimensional shapes,” he added as he bent and twisted the line of beads.
“These three-dimensional shapes are highly irregular, sort of like the teeth in a key, and they have a lock-key fit with other molecules in the cell. Often, the proteins will catalyze reactions, or they’ll form structural molecules, or linkers, or parts of the molecular machines that Michael Behe writes about. This specific three-dimensional shape, which allows proteins to perform a function, derives directly from the one-dimensional sequencing of amino acids.”
Then he pulled some of the beads apart and began rearranging their order. “If I were to switch a red one and a blue one, I’d be setting up a different combination of force interactions and the protein would fold completely differently. So the sequence of the amino acids is critical to getting the long chain to fold properly to form an actual functional protein. Wrong sequence, no folding—and the sequence of amino acids is unable to serve its function.
“Proteins, of course, are the key functional molecule in the cell; you can’t have life without them. Where do they come from? Well, that question forces a deeper issue—what’s the source of the assembly instructions in DNA that are responsible for the one-dimensional sequential arrangements of amino acids that create the three-dimensional shapes of proteins? Ultimately,” he emphasized, “the functional attributes of proteins derive from information stored