Question

why trna acts like adaptor?

Answer 1

Translation of the nucleotide sequence (codons) into amino acids is accomplished by tRNA molecules. These RNA molecules act as adaptors between the codons and the amino acids that they specify. This was proposed by Francis Crick in 1955 when he gave the "Adaptor Hypothesis" stating that prior to the incorporation of the amino acid into the polypeptide chain, the amino acids bind to specific adaptor molecules (which came to be known as tRNA later) that possess unique surfaces that bind specifically to bases on the RNA template.

Amino acids cannot directly interact with the codons which was earlier predicted as correct. This is because of the following reasons:

• Specific chemical groups on the four bases of RNA mostly interact with water soluble groups (hydrophilic). However, the side groups of many amino acids prefer interactions with water insoluble groups (hydrophobic).
• Even if the RNA was able to fold into conformations to allow the binding of the amino acid to the codon which was earlier predicted, it is unlikely that the RNA would be able to distinguish between chemically similar amino acids.

Therefore, Francis Crick gave the "Adaptor Hypothesis".