 TRNA molecule to which an amino acid is attached are said to be charged and Those TRNA molecules to which amino acids are not attached. They are called Uncharged charging requires an a soil linkage between the carboxyl group of the amino acid and the true 2 prime or 3 prime hydroxyl group of the adenosine nucleotide that protrudes from the acceptor stem at the 3 prime end of the TRNA This a sigh linkage is a high energy bond Because its hydrolysis results in a large change in the free energy This is Significant for protein synthesis the energy released When this a sigh bond is broken is coupled to the formation of peptide bond That link amino acids to each other in the polypeptide chain. So, you do a Sile linkage a high energy bond a very significant because if you have a sigh linkage TRNA or amino acid linked When it comes to MRNA and ribosome, then this a sigh linkage break Its breakage is a very high energy that will be released and this energy will be utilized For the synthesis of peptide bond because now this amino acid has been released from here It has to be added to the polypeptide from before through the formation of peptide Bond or a peptide bond the formation you have it itself requires energy or a energy to have a Sile linkage keep break down All amino acid TRNA synthetases Attach and a minocid to a TRNA in two enzymatic steps First is adenylation and the second is TRNA charging Step one is adenylation in which the amino acid reacts with ATP To become adenylated With the concomitant release of pyrophosphate. So the first step is This amino acid reacts with ATP and after reacting this adenylated Hatha or saati pyrophosphate you have a release of the a adenylation refers to transfer of a mp as Opposed to adenylation Which would indicate the transfer of adenylated in in so adenylation or adenylation? You do different reactions the principal driving force for the adenylation Reaction is the subsequent hydrolysis of pyrophosphate by pyrophosphate is As a result of adenylation The amino acid is attached to adenylic acid via a high energy ester bond In which the carbonyl group of the amino acid is joined to the phosphoryl group of the Amp Step 2 in this is the TRNA charging In which the adenylated amino acid which remains tightly bound to the synthase reacts with TRNA. Now, the second is that this adenylated Amino acid reacts with TRNA This reaction results in the transfer of the amino acid To the 3 prime end of the TRNA via the 2 prime or 3 prime hydroxyl and the release of Amp. So, this type of amino acid is attached to the 3 prime end of the TRNA There are two classes of TRNA synthetases Class 1 enzymes attach the amino acid to the 2 prime end OH of the TRNA and are generally monomeric Class 2 enzymes attach the amino acid to the 3 prime OH of the TRNA and are typically dimeric or tetrameric. So, there are two classes. One is attached to the 2 prime OH and the other class 2 is attached to the 3 prime OH and will attach it to the amino acid Although the initial coupling between the TRNA and the amino acid is different Once released from the synthetase the amino acid rapidly Equilibrates between attachment at the 3 prime OH and the 2 prime OH So here you can see this is the reaction. So in the first reaction, this is a amino acid it Attacks this ATP molecule and now this becomes a mino-acyl Amp or you can see this is adenylated Amino acid and this pyrophosphate is released. So in the second step this TRNA joins with this adenylated amino acid and in this way this a mino-acyl TRNA complex is formed and Amp is released. These are the two steps first step and second step These are the two steps in the charging of TRNA. Each of the 20 amino acids is attached to the appropriate TRNA by a single dedicated TRNA synthetase Because most amino acids are specified by more than one codon It is not uncommon for one synthetase to recognize and charge More than one TRNA and this is known as iso accepting TRNAs Nevertheless, the same TRNA synthetase is Responsible for charging all the TRNAs for a particular amino acid So this is a mino-acyl. If it is a special amino acid, then all the TRNAs are to be charged One of the TRNA synthetase will be used. Thus one and only one TRNA synthetase attaches each mino-acyl to all the appropriate TRNAs