Question

Biochemical and genetic experiments have demonstrated that the _________ of tRNA are important for recognition by its cognate aminotransferase-tRNA synthetase.

Answer 1

The anticodon loop and other structural elements in tRNA are critical for specific recognition by aminoacyl-tRNA synthetases, serving as identity elements within a 'second genetic code'.

Step-by-step explanation:

Biochemical and genetic experiments have identified that the anticodon loop and other structural features of transfer RNA (tRNA) are crucial for recognition by its cognate aminoacyl-tRNA synthetase (aaRS). The process of tRNA recognition by aaRS is a sophisticated mechanism that entails distinct interaction sites within the tRNA molecule. These sites, or identity elements, can be seen as part of a 'second genetic code' that determines the specificity of tRNA for its corresponding amino acid. The tRNA structure, which incorporates these identity elements, has evolved within the constraints of maintaining a functional shape for participation in translation while also differentiating between various tRNAs. Genetic code fidelity relies significantly on tRNAs being accurately recognized and aminoacylated by their cognate aaRS, an action that requires co-evolution and fine-tuning between the 3D structure and chemical properties of the tRNA and the recognition patterns of the aaRS.

Answer 2

Answer: Acceptor stem and anticodon loop.

Step-by-step explanation:

Transfer RNA (tRNA) is a small RNA nucleic acid involved in protein synthesis (translation). Each tRNA molecule has two important areas:

1. A region of trinucleotides, called the anticodon
2. A region where a specific amino acid binds.

During translation, the ribosome reads the sequence of the mRNA in groups of three bases to assemble the protein. So, in the mRNA chain there are codons, set of three bases, which determine the amino acid to be added to the peptide chain. The tRNA transfers the amino acid to the ribosomes, and then arranges them along the messenger RNA (mRNA) molecule. Then, the tRNA must have an anticodon that is complementary to the codon. Each type of tRNA is specifically combined with 1 of the 20 amino acids to be incorporated into proteins.

This means, during translation, each time an amino acid is added to the growing chain, a tRNA molecule is formed whose base pairs have a complementary sequence with mRNA molecule, ensuring that the appropriate amino acid is inserted into the protein. So, tRNA is a key link between RNA transcription and the translation of that RNA into protein. On the other hand, aminotransferases are enzymes responsible for attaching amino acids to the 3ʹ‐end of cognate tRNAs.

The acceptor stem is the site of attachment of amino acids to tRNA, and anticodon loop is the site of tRNA that is complementary to the codons found in mRNA (that determine the amino acid that will be added) This means, both parts are important for recognition, because the acceptor stem is where the amino acid is, and the anticodon loop ensures that the appropriate amino acid is inserted into the protein.