How is RNA defined?

RNA, or ribonucleic acid, is defined as a single strand of nucleotides that plays a crucial role in the synthesis of proteins. It acts as a messenger, carrying genetic information from DNA to the ribosomes, where proteins are assembled. The structure of RNA consists of ribose sugars, phosphate groups, and nitrogenous bases (adenine, uracil, cytosine, and guanine), which allow it to perform various types of functions within the cell, particularly in the processes of transcription and translation.

During transcription, RNA is synthesized based on the sequence of a gene encoded in DNA. Subsequently, this RNA (specifically messenger RNA, or mRNA) is translated into a specific protein by ribosomes, employing transfer RNA (tRNA) and ribosomal RNA (rRNA) as well. This makes RNA essential for protein synthesis, as it directly connects the genetic code to the functional molecules that are proteins.

The other options represent concepts that do not accurately describe RNA's structure or function, underscoring the importance of recognizing RNA's unique role in biology. For example, RNA is not double-stranded like DNA, and it does not carry out energy transport like ATP, nor is it a chain of amino acids,