Just went to a great seminar~An Expanding Genetic Code

Our Biochem Teacher went abroad to attend a meeting, and a much better one came to teach this weak. Finnaly a good teacher who can at least get us intrested in Biochem once again. Today, he told us there was this seminar when the name "Peter Schultz" appeared in the text book. He said that this guy might get a Nobel prize in the near future for his great work, and that Schultz HIMSELF would be speaking here at school this afternoon. Finally a great seminar that I have time to go! And I just went "Wow" and grasped the chance.
Actually, I never thought Biochem could be so intresting before this. The title was "An Expanding Genetic Code", and he talked about how he changed a gene coden to represent a 21st amino acid, in addition to the normal 20 amino acids found in organisms. He thought "Why are there only 20 amino acids encoded in the genome in all life? What if God also worked on Sunday, would the number be something like 21, or 22?" (Which makes me think: How come Christens can always add "God" to every thing they think of?) And so they(him and his team) started out on a project to add more amino acids to an organism (E.coli actually) and see what could happen, and see if it will have an advantage or disadvantage over life with only 20.
In the process of translating mRNA (which is a info carier transcribed from DNA) into proteins, ribosomes read the mRNA strand and tRNAs bring the correct amino acid to ribosomes and add the amino acids up into a polypeptide chain (a precursor to proteins). In the process, an enzyme called "Aminoacyl-tRNA synthatase" load tRNAs with the correct amino acids.
So they tried to mutate tRNAs and Aminoacyl-tRNA synthatases to carry and load the specific amino acid they wanted to add. Surprisingly, it took them 6 years, several tries to produce what they want. I guess you need incredible patience to succeed in such an ambitious and ground breaking research, and you need lots of funding to do it, too. So it took them 6 years just to get the right tool they needed, now they finally are starting to add unnormal amino acids to E.coli.
They tried several different kinds of amino acids, even artificially synthesized amino acids with unseen-before side chains, with much success. Even more astonising, he said that because most triplet codes in the genome are already used for important Amino acids, only 2 not commenly used codens could be utilized to introduce additional ones. In order to add more, he did further mutating to get tRNAs and Aminoacyl-tRNA synthatases that use codons with 4 basepairs! And success again! Now there are already major pharmaceutical companies using these methods to develop new protein based medicines. In conclusion, he said that the proteins of life are constrained by the genetic codes, to only 20 amino acids, with no apperent reason.
What's intresting is that in the making of those tools, they made large mutation pools, insert into E.coli, and use negative selection to get the one they wanted, by adding genes that make the unsuccessful ones die off. What's more, in the adding of 4-based codens, it also competes with the less seen triplet codes which has a same sequence as on the 4-based. This is very like the development of T and B lymphocytes of the immune system, which also selects the sucessfull cells and let the failed ones die off. Which also makes me think of the similarity to the process of evolution of life it self. How intresting it is that the rule: "survival of the fittest" applies not only to the evolution of species, the developement of lymphocytes, but also to genetic engineering techneques. Maybe this is THE ULTIMATE RULE of life. Wonder if it also applies to anything else associated with life?