Question

Why must tRNAs have both unique structural features and common structural features? There are two transfer RNAs that will carry methionine, Met-tRNAi and Met-tRNAmet, with reasons, suggest: ONE unique structural feature ONE common structural feature

Answer 1

There are both common and unique structural features in a t-RNA to perform its functions. A t-RNA function to attach amino acid by recognizing the codons present in the mRNA in the process of translation. Obviously, if it is to recognize the different amino acids that need to be added, then the anticodon loop of each t-RNA must be unique for the amino acid concerned. Again, in order to complete this task, a t-RNA interacts with common enzymes, ribosomes, etc so it has some common structural features as well.

For example, in case of Met-tRNAi and Met-tRNAmet, the common structural feature would be the conserved site of attachment present at the 3' end (CCA site). The unique structural features would be the variable arm of the t-RNA, the difference in position or amount of dihydrouridine (D) in D-loops, or Pseudouridine in T-loops.