Final answer:
The synthesis of a polypeptide requires the most energy for each new bond formed because of the energy-intensive process of translation where peptide bonds are created to form the primary structure of proteins. These proteins perform vital functions in the cell, and due to the length and complexity of protein chains, this process consumes more energy than the synthesis of other molecules like DNA, mRNA, rRNA, or tRNA.
Step-by-step explanation:
The question asks which molecule requires the most energy for new bond formation during its synthesis. Among the options provided, the synthesis of a polypeptide consumes the most energy. This is because the translation process involves the decoding of an mRNA message by a ribosome to form a polypeptide chain, where amino acids are covalently bonded together via peptide bonds in a dehydration synthesis reaction.
This reaction is energy-intensive, with each addition of an amino acid to the growing polypeptide requiring ATP. In comparison, the synthesis of DNA, mRNA, rRNA, and tRNA involves forming phosphodiesterase bonds, which is a less energy-consuming process than forming the peptide bonds of polypeptides.
During protein synthesis, each individual amino acid links to the growing polypeptide chain by the formation of a peptide bond between its amino group (NH₂) and the carboxyl group (COOH) of the previous amino acid in the chain. This crucial step happens on the ribosome and is vital for building the primary structure of proteins.
Given the lengthy nature of protein chains, which can contain from 50 to over 1000 amino acids, and considering the major role that proteins play in virtually every cellular function, it becomes clear that the synthesis of polypeptides is the most energy-demanding process among the options listed.