Final answer:
Class I aminoacyl-tRNA synthetases attach an amino acid to the tRNA by forming an ester bond at the 2'-OH of the terminal adenylate. This process is crucial for the activation of tRNA and subsequent protein synthesis.
Step-by-step explanation:
Class I aminoacyl-tRNA synthetases add the amino acid (aa) to the 2'-OH group of the terminal adenylate at the 3' end of the tRNA. During tRNA "charging," these enzymes catalyze the transfer of the activated amino acid to the tRNA, forming a high-energy ester bond, which is later used to drive the formation of the peptide bond during protein synthesis.
The activation of tRNA involves the attachment of an amino acid to the 3' end of the tRNA, which always has an adenosine (A) with a free 3' –OH group, followed by two cytosines (C), making up the ACC sequence. The 3' terminal trinucleotide C-C-A (3') is specifically recognized and utilized by these synthetases for the attachment process.