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15. Beskrive tRNAs adapterfunktion (anticodon) og aminoacyl 3'-ende (aktiveret aminosyre)
Stryer, s.815-8
Devlin, s. 82

Transfer RNA serves as the adapter molecule that binds to a specific codon of the mRNA and brings with it an amino acid for incorporation into the polypeptide chain.

Both functions are reflected in the fact that tRNA has two essential parts:

 The 3’-OH terminal CCA sequence – to which specific amino acids are attached enzymatically. The CCA sequence is located on the amino acid acceptor stem, which is 7 nucleotides long. The CCA sequence is not base paired. The amino acid attachment site is the 3’-OH group of the adenosine residue of the CCA sequence.

The anticodon triplet, which recognizes the complementary mRNA sequence. The anticodon triplet is found on the anticodon loop - a sequence 7 nucleotides long located almost in the middle of the tRNA molecule.

Three nucleotides in the mRNA make a codon. The codon and anticodon triplets form base pairs during peptide-bond formation. The base pairing is possible due to the base-stacking of the anticodon triplet making a partial helical structure that is capable of binding to it complementary region on the mRNA.

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