What percentage of a cell's energy is used for protein synthesis?

The correct answer indicates that a significant portion of a cell's energy, approximately 80-90%, is dedicated to protein synthesis. This substantial percentage reflects the high demand for ATP required during the various stages of protein production, including transcription and translation. Cells spend considerable energy to:

1. Synthesize mRNA from DNA in transcription, which involves unwinding DNA, synthesizing RNA nucleotides complementary to the template strand, and processing the mRNA.
2. Translate the mRNA into a polypeptide chain, which requires the assembly of ribosomes, tRNA, and amino acids. This process includes the energy-intensive steps of codon recognition, peptide bond formation, and translocation.
3. Fold and modify proteins post-translation, where chaperone proteins often assist in proper folding, which can also require energy.

The high energy expenditure for these processes underscores the importance of proteins in cellular function, regulation, and structure, making protein synthesis a central focus of cellular metabolism. Understanding this energy allocation is essential for grasping how cells prioritize their functions to maintain life and respond to various stimuli.