what is the role of the a-site in translation
Translation (biology) The ribosome has three sites for tRNA to bind. They are the aminoacyl site (abbreviated A), the peptidyl site (abbreviated P) and the exit site (abbreviated E). With respect to the mRNA, the three sites are oriented 5’ to 3’ E-P-A, because ribosomes move toward the 3' end of mRNA. The A-site binds the incoming tRNA with the complementary codon on the mRNA. The P-site holds the tRNA with the growing polypeptide chain. The E-site holds the tRNA without its amino acid. When an aminoacyl-tRNA initially binds to its corresponding codon on the mRNA, it is in the A site. Then, a peptide bond forms between the amino acid of the tRNA in the A site and the amino acid of the charged tRNA in the P site. The growing polypeptide chain is transferred to the tRNA in the A site. Translocation occurs, moving the tRNA in the P site, now without an amino acid, to the E site; the tRNA that was in the A site, now charged with the polypeptide chain, is moved to the P site. The tRNA in the E site leaves and another aminoacyl-tRNA enters the A site to repeat the process.[6]
English-speaking world Because English is so widely spoken, it has often been referred to as a "world language", the lingua franca of the modern era,[17] and while it is not an official language in most countries, it is currently the language most often taught as a foreign language.[18] It is, by international treaty, the official language for aeronautical[19] and maritime[20] communications. English is one of the official languages of the United Nations and many other international organizations, including the International Olympic Committee. It is also one of two co-official languages for astronauts (besides the Russian language) serving on board the International Space Station.[citation needed]