[Campbell Biology P.401] Which statement accurately describes aspects of polypeptide chain e... | Practice Question

Which statement accurately describes aspects of polypeptide chain elongation during translation?

  • A: Amino acids are added one by one to the N-terminus of the growing chain.
  • B: The mRNA is moved through the ribosome in a 3' to 5' direction.
  • C: Energy for codon recognition and translocation during elongation is primarily provided by the hydrolysis of GTP.
  • D: The entire elongation cycle in bacteria takes approximately one second per amino acid added.

Explanation

During elongation, amino acids are added to the C-terminus of the growing polypeptide chain. The mRNA moves through the ribosome in a 5' end first manner. Both codon recognition and translocation steps require energy, which is provided by the hydrolysis of GTP. In bacteria, the elongation cycle is very rapid, taking less than a tenth of a second per amino acid addition.