What is the primary role of RNA in living cells?

The primary role of RNA in living cells is protein synthesis. RNA, or ribonucleic acid, serves as a crucial intermediary between the genetic information encoded in DNA and the production of proteins, which are essential for numerous functions within the cell.

During the process of transcription, messenger RNA (mRNA) is synthesized from a DNA template, carrying the genetic instructions from the DNA in the nucleus to the ribosomes in the cytoplasm, where proteins are made. At the ribosomes, mRNA is translated into a specific sequence of amino acids, which then fold into functional proteins.

This role of RNA is fundamental to the expression of genes and the overall functioning of the cell. While RNA does have other functions, such as forming part of the structure of ribosomes (ribosomal RNA) and carrying amino acids to ribosomes (transfer RNA), its primary and most critical function is indeed in protein synthesis.

The other options do not accurately reflect the main role of RNA. Energy storage is primarily handled by molecules like ATP and glucose. Cellular structure is typically maintained through proteins and lipids. Genetic information storage is the primary function of DNA, not RNA.