Question

Describe the process by which tRNAs are charged with an amino acid. How is it possible that a specific tRNA will only be bound to a very particular amino acid, and that a different tRNA will also only be bound to a particular amino acid that is different from the first? Provide details on each component involved and of how the recognition is achieved. I am not asking for information about the energetics of the process, just about the specificity of the process.

Answer 1

The tRNA is a type of RNA which is able to carry an amino acid to ribosomes and add the same to the growing polynucleotide chain. The charged tRNA is the one which has an amino acid which is a 3 nucleotide attached to it. Each of the tRNA is charged by attaching an amino acid to it with help of amimoacyl tRNA synthetase. The enzyme ensures the attachment of the correct amino acid to the tRNA which consists of an anticodon for the amino acid. The first step is the activation of the amino acid by addition of the ATP and it leads to the formation of aminoacyl adenylate. After the activation is done, the aminoacyl adenylate is attached to tRNA and this lead to binding of the amino acid and releasing aminoacyl tRNA and AMP.

The tRNA is able to bind to only specific or a particular type of amino acid because of the specific anticodon-codon base pairing. The tRNA is able to bind only one type of amino acid because of the anti-codon it carry and this perfectly codes for an amino acid which is the codon. The mRNA codon in three nucleotides forms the amino acid and it binds specifically only to the anti-codon located in tRNA and they are specific to each other. Hence, the specific codon – anticodon complementation leads to making each tRNA specific for only one type of amino acid.