For example, Helicobacter pylori has glutaminyl t RNA synthetase missing.Thus, glutamate t RNA synthetase charges t RNA-glutamine(t RNA-Gln) with glutamate.This leads to charging of the t RNA by a chemically related amino acid.
The covalent attachment to the t RNA 3’ end is catalyzed by enzymes called aminoacyl t RNA synthetases.
During protein synthesis, t RNAs with attached amino acids are delivered to the ribosome by proteins called elongation factors, which aid in association of the t RNA with the ribosome, synthesis of the new polypeptide and translocation (movement) of the ribosome along the m RNA.
In the genetic code, it is common for a single amino acid to be specified by all four third-position possibilities, or at least by both pyrimidines and purines; for example, the amino acid glycine is coded for by the codon sequences GGU, GGC, GGA, and GGG.
Other modified nucleotides may also appear at the first anticodon position—sometimes known as the "wobble position"—resulting in subtle changes to the genetic code, as for example in mitochondria.
Each type of t RNA molecule can be attached to only one type of amino acid, so each organism has many types of t RNA.
Because the genetic code contains multiple codons that specify the same amino acid, there are several t RNA molecules bearing different anticodons which carry the same amino acid.If the t RNA's anticodon matches the m RNA, another t RNA already bound to the ribosome transfers the growing polypeptide chain from its 3’ end to the amino acid attached to the 3’ end of the newly delivered t RNA, a reaction catalyzed by the ribosome.A large number of the individual nucleotides in a t RNA molecule may be chemically modified, often by methylation or deamidation.Each t RNA is aminoacylated (or charged) with a specific amino acid by an aminoacyl t RNA synthetase.There is normally a single aminoacyl t RNA synthetase for each amino acid, despite the fact that there can be more than one t RNA, and more than one anticodon, for an amino acid.The Protein Data Bank (PDB) codes for the structural models used as end points of the animation are given. Once translation initiation is complete, the first aminoacyl t RNA is located in the P/P site, ready for the elongation cycle described below.