Final answer:
Four ATP equivalents are consumed during the translation of each amino acid into a polypeptide. This includes two ATP equivalents during the activation stage and the equivalent of two ATP from GTP hydrolysis during elongation.
Step-by-step explanation:
For each amino acid incorporated into a polypeptide, four ATP equivalents are used up during translation. This energy expenditure occurs in two stages:
- The first stage is the activation of amino acids, where an amino acid is attached to its corresponding tRNA by an aminoacyl tRNA synthetase. This reaction consumes two ATP equivalents as ATP is initially hydrolyzed to AMP and pyrophosphate (which is equivalent to the energy of two ATPs because the breaking of two high-energy phosphoanhydride bonds occurs).
- The second stage is the elongation of the polypeptide chain where amino acids are sequentially added to the growing chain. This involves the hydrolysis of GTP for each aminoacyl-tRNA that enters the ribosome and for translocation. Although GTP is hydrolyzed instead of ATP, for the purpose of energy equivalence, we consider GTP to have the same energy contribution as ATP.
The process of translation is highly efficient, with E. coli being capable of adding an amino acid every 0.05 seconds, allowing a 200-amino acid polypeptide to be synthesized in approximately 10 seconds.