Correct Response: A. The primary role of tRNA molecules is to bring the appropriate amino acids to the ribosome during translation. A tRNA molecule accomplishes this by matching its anticodon (a sequence of three nucleotides that designates the specific amino acid attached to the tRNA molecule) to the codon sequences in the mRNA molecule is translated. The anticodon sequence will pair only with the complementary mRNA codon, thus ensuring that the correct amino acid is added to the polypeptide chain.
The amino acids that are delivered to the ribosome by tRNA molecules are attached to the growing polypeptide chain by the large ribosomal subunit (B). Introns (non-coding regions) are eliminated from the mRNA sequence (C) by a structure called a spliceosome before the mRNA leaves the nucleus. Termination of the growing polypeptide chain (D) occurs when the ribosomal complex reaches a termination codon, which signals a protein called a release factor to bind and release the polypeptide chain.
