Aminoacyl-tRNA is tRNA

Transfer RNA

Transfer RNA is an adaptor molecule composed of RNA, typically 73 to 93 nucleotides in length, that is used in biology to bridge the three-letter genetic code in messenger RNA with the twenty-letter code of amino acids in proteins. The role of tRNA as an adaptor is best understood by...

 (also known as transfer ribonucleic acid) to which its cognated amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

 is adhered. Its role is to deliver the amino acid to the ribosome

Ribosome

A ribosome is a component of cells that assembles the twenty specific amino acid molecules to form the particular protein molecule determined by the nucleotide sequence of an RNA molecule....

 where it will be incorporated into the polypeptide chain that is being produced. A specific amino acid is added to each tRNA, which is crucial since it means that only that particular amino acid will be incorporated when the anticodon of that tRNA fits (can form a transient base pair

Base pair

In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...

 with) the next codon of the mRNA

Messenger RNA

Messenger RNA is a molecule of RNA encoding a chemical "blueprint" for a protein product. mRNA is transcribed from a DNA template, and carries coding information to the sites of protein synthesis: the ribosomes. Here, the nucleic acid polymer is translated into a polymer of amino acids: a protein...

 that is being translated into protein.

The specific linkage of the correct amino acid to each tRNA is accomplished by aminoacyl tRNA synthetase

Aminoacyl tRNA synthetase

An aminoacyl tRNA synthetase is an enzyme that catalyzes the esterification of a specific amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl-tRNA. This is sometimes called "charging" the tRNA with the amino acid...

s. Due to the degeneracy of the genetic code

Genetic code

The genetic code is the set of rules by which information encoded in genetic material is translated into proteins by living cells....

, some of the different tRNAs have the same amino acid attached to them.

Synthesis

Aminoacyl-tRNA (also known as charged tRNA) is produced in two steps; amino acid activation and transfer. The first step is the adenylation of the amino acid, which forms aminoacyl-AMP:

Amino acid + ATP ↔ Aminoacyl-AMP + PP_i

Then, the amino acid residue is transferred to the tRNA:

Aminoacyl-AMP + tRNA ↔ Aminoacyl-tRNA + AMP

The net reaction is:

Amino acid + ATP + tRNA ↔ Aminoacyl-tRNA + AMP + PP_i

The net reaction is only energetically favourable because the pyrophosphate

Pyrophosphate

In chemistry, the anion, the salts, and the esters of pyrophosphoric acid are called pyrophosphates. Any salt or ester containing two phosphate groups is called a diphosphate. As a food additive, diphosphates are known as E450.- Chemistry :...

 is hydrolysed; that reaction is highly energetically favourable and drives the other reactions. All of these reactions take place inside the aminoacyl-tRNA synthetase specific for that tRNA.

Drugs that target aminoacyl-tRNA binding to ribosomal subunit

Certain drugs like tetracycline prevent the aminoacyl-tRNA from binding to the ribosomal subunit in prokaryotes.