Thursday, September 16, 2010

Creator of the Code

Several sources of wonder and awe concerning cells have been addressed in recent posts. These include their complexity, organization, design, information content, replicating capacity, and synthesizing ability. So far, we have not specifically dealt with the most fascinating question of all with regard to the cell’s ability to synthesize proteins: How does the cell do that?

The cell is the lowest organizational structure with ability to perform all activities necessary for life. Biology’s focus, therefore, centers on understanding how a cell works. How, for example, does growth occur from a single cell to a complete living organism possessing trillions of cells? How are the instructions for completion of such a task given and followed? The answer is found in understanding how the cell’s genetic code works. That code contains the instructions for assembling the twenty existing amino acids into the tens of thousands of different proteins needed to build the complete, efficiently functioning organism.

The cell’s molecular chain of command reads DNA --> RNA --> proteins. In addition to preserving and passing inheritance along through multiple generations, DNA is also the template for producing an even more versatile molecule--RNA, containing the code for the protein production. A long strand of RNA consists of a sequence of only four nucleotides, abbreviated A, G, C, and U for short. The sequence may be thousands of nucleotides long. They occur in any order. The same letter may sometimes occur multiple times consecutively. Example: UUGUUUGGCUCA. Embedded in the long RNA strands are sections thousands of nucleotide letters long.

Now the story becomes more fascinating and needs more explanation. If one nucleotide letter were to signal one amino acid, only four amino acids could be specified. A two-letter code using arrangements of the four letters in any order, with possible repeated letters, could code for as many as sixteen amino acids--still not enough for the existing twenty. But if a three-letter code is used, making use of all possible arrangements, it is possible to achieve 64 different groupings, more than enough to specify all twenty amino acids. These three-letter sequences are called codons. Several of the codons signal “stop” or “start” in the translation process.

Consider a modern supermarket analogy. In the bulk foods section of our local supermarket there is a wonderful selection of products which customers may self-dispense and self-package. Once I have bagged my product I proceed to the scales and type in the proper digital code for that product. Let’s say the digital code is 313 for our favorite sesame oat bran sticks. That number code, along with the proper equipment, has been programmed by the store manager to “synthesize” a gummed label with specific details of product name, weight, unit price, total cost, and store name.

Imagine supermarket customers claiming such an event sequence is merely the result of blind chance. No, the supermarket bulk purchase department is obviously intelligently designed as is its coding system. The process of coding for the appropriate amino acids, followed by the synthesis of tens of thousands of specific proteins by the cell’s manufacturing centers-- ribosomes in the cell’s cytoplasm--makes the accomplishments of our supermarket’s bulk purchase department minimal, by comparison.

The proteins produced are not just any proteins. They are the correct proteins needed to produce a specimen of a particular species. The conclusion that the cell’s protein coding apparatus is intelligently designed is inescapable as is the rational belief in the existence of the Creator described in Holy Scripture.