"The biochemical language of the genetic code uses short strings of three nucleotides (called codons) to symbolize commands -- including
start commands,
stop commands,
and codons
that signify each of the 20 amino acids used in life.After the information in DNA is transcribed into mRNA, a series of codons in the mRNA molecule instructs the ribosome which amino acids are to be strung in which order to build a protein.
Translation works by using another type of RNA molecule called transfer RNA (tRNA). During translation, tRNA molecules ferry needed amino acids to the ribosome so the protein chain can be assembled.
Each tRNA molecule is linked to a single amino acid on one end, and at the other end exposes three nucleotides (called an anti-codon). At the ribosome, small free-floating pieces of tRNA bind to the mRNA. When the anti-codon on a tRNA molecule binds to matching
For the genetic code to be translated properly, each tRNA molecule must be attached to the proper amino acid that corresponds to its anticodon as specified by the genetic code. If this critical step does not occur, then the language of the genetic code breaks down, and there is no way to convert the information in DNA into properly ordered proteins. So how do tRNA molecules become attached to the right amino acid?
Cells use special proteins called aminoacyl tRNA synthetase (aaRS) enzymes to attach tRNA molecules to the "proper" amino acid under the language of the genetic code. Most cells use 20 different aaRS enzymes, one for each amino acid used in life. These aaRS enzymes are key to ensuring that the genetic code is correctly interpreted in the cell.
Yet these aaRS enzymes themselves are encoded by the genes in the DNA. This forms the essence of a "chicken-egg problem": aaRS enzymes themselves are necessary to perform the very task that constructs them.
How could such an integrated, language-based system arise in a step-by-step fashion? If any component is missing, the genetic information cannot be converted into proteins, and the message is lost. The RNA world is unsatisfactory because it provides no explanation for how the key step of the genetic code -- linking amino acids to the correct tRNA -- could have arisen." EN&V
Shall he that contendeth with the Almighty instruct him?
Job 40:2