![]() A large number of the individual nucleotides in a tRNA molecule may be chemically modified, often by methylation or deamidation. If the tRNA's anticodon matches the mRNA, another tRNA 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 tRNA, a reaction catalysed by the ribosome. During protein synthesis, tRNAs with attached amino acids are delivered to the ribosome by proteins called elongation factors, which aid in association of the tRNA with the ribosome, synthesis of the new polypeptide, and translocation (movement) of the ribosome along the mRNA. The covalent attachment to the tRNA 3’ end is catalysed by enzymes called aminoacyl tRNA synthetases. ![]() Because the genetic code contains multiple codons that specify the same amino acid, there are several tRNA molecules bearing different anticodons which carry the same amino acid. Each type of tRNA molecule can be attached to only one type of amino acid, so each organism has many types of tRNA. On the other end of the tRNA is a covalent attachment to the amino acid that corresponds to the anticodon sequence. The anticodon forms three complementary base pairs with a codon in mRNA during protein biosynthesis. One end of the tRNA matches the genetic code in a three-nucleotide sequence called the anticodon. The mRNA encodes a protein as a series of contiguous codons, each of which is recognized by a particular tRNA. While the specific nucleotide sequence of an mRNA specifies which amino acids are incorporated into the protein product of the gene from which the mRNA is transcribed, the role of tRNA is to specify which sequence from the genetic code corresponds to which amino acid. As such, tRNAs are a necessary component of translation, the biological synthesis of new proteins in accordance with the genetic code. ![]() Complementation of a 3-nucleotide codon in a messenger RNA (mRNA) by a 3-nucleotide anticodon of the tRNA results in protein synthesis based on the mRNA code. Transfer RNA (tRNA) does this by carrying an amino acid to the protein synthesizing machinery of a cell called the ribosome. The mature tRNA follows an opposite pattern with tRNAs from Bacteria being usually longer (median = 77.6 nt) than tRNAs from Archaea (median = 76.8 nt), with eukaryotes exhibiting the shortest mature tRNAs (median = 74.5 nt). tRNAs genes from Bacteria are typically shorter (mean = 77.6 bp) than tRNAs from Archaea (mean = 83.1 bp) and eukaryotes (mean = 84.7 bp). Transfer RNA (abbreviated tRNA and formerly referred to as sRNA, for soluble RNA ) is an adaptor molecule composed of RNA, typically 76 to 90 nucleotides in length (in eukaryotes), that serves as the physical link between the mRNA and the amino acid sequence of proteins. The interaction of tRNA and mRNA in protein synthesis.
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