Question

During elongation of proteins during protein synthesis tRNA with the amino acid that matches its anticodon binds to the codon on the mRNA. each new amino acid is first transferred to the anticodon of the tRNA. anticodons on the ribosomes recognize the codons on the mRNA and attach the correct amino acids. ribosomes move along the DNA. RNA polymerase II uses the codons on the mRNA to polymerize the protein.

Answer 1

C. Anticodons on the ribosomes recognize the codons on the mRNA and attach the correct amino acids. -------> TRUE

Elongation:

Protein synthesis occurs in three steps namely, initiation, elongation and termination. During initiation, the mRNA, tRNA comes together at the ribosome and the translation initiated at the start codon (AUG, codes for methionine).

During elongation, amino acids are added to the growing polypeptide chain according to the mRNA sequence. The aminoacyl-tRNA molecules are picked up by the elongation factors in the presence of GTP, Which enters the A site. On the ribosome, the mRNA codon bound at the A site will be matched with appropriate anticodon of aminoacyl-tRNA. The translational machinery plays a key role in this selection and proofreading.

After binding of correct codon and anti-codon, the new amino acid is linked to the growing polypeptide chain in the P –site (peptidyl site) by a peptide bond. This process is catalysed by an enzyme peptidyl transferase located at the peptidyl transferase center of the large ribosomal subunit. A new peptidyl-tRNA now occupies the A site. The empty tRNA now moves to the E site and this process is facilitated by another elongation factor (eEF 2) and GTP. The new peptidyl-tRNA moves to the P site, and the cycle repeats until it reads a stop codon. The following picture depicts the various stages in elongation.