TranslaShun & the Shun-Ettes!

Dig deep, deep, deep into your hippocampus and recall that protein synthesis on the ribosome is a series of "SHUNS:" That is, translation begins with initiation, continues with elongation, and ends with termination.

Initiation refers to the preliminary assembly of small subunit of the ribosome, the mRNA to be translated, and the first amino acid (always methionine) in the form of amino-acyl-tRNA.

Elongation is the process whereby the completed ribosome reads the genetic code as it moves along the mRNA. Recall that the code is comprised of nucleotide triplets, or three-letter nucleotide "words" corresponding to specific amino acids. These codons match anticodons on the t-RNA specific to that amino acid, which allows the ribosome to "line up" the aminoacy t-RNAs in the correct sequence.

Termination, of course, usually refers to either a pink slip or sending a robot back in time to whack some kid. In this special case, however, it refers to the process by which translation comes to an end: the ribosome encounters a stop codon, flies apart, and releases the mRNA and the newly formed protein.

Translation is an exquisitely complex, efficient and beautiful process. If you consider the tools nature has to work with, the accuracy required, the speed with which it occurs, and the scale at which it happens, it's almost miraculous that it works at all. Somebody once said that a translating ribosome was a machine made of water balloons, assembling tinkertoys while rolling down a staircase. But you can also think of it as a nanorobot reading instructions off a tape. Either way, it's cool.

Figure: Ribo-Robotos-Rock. The translation process.