What is encoded by most genes?

Most genes encode polypeptides, which are chains of amino acids that fold into functional proteins. The process of gene expression begins with the transcription of DNA into messenger RNA (mRNA). This mRNA then serves as a template for translation, where ribosomes read the sequence of nucleotides and assemble the appropriate amino acids in the correct order to form a polypeptide chain. Polypeptides may undergo post-translational modifications to become fully functional proteins that perform various roles in the cell, including acting as enzymes, structural components, signaling molecules, and more.

While ribosomal RNA, transfer RNA, and micro RNA play essential roles in cellular processes, particularly in protein synthesis and gene regulation, they are not themselves the direct products of most genes. Ribosomal RNA is a component of the ribosomes, transfer RNA carries amino acids during translation, and micro RNA is involved in the regulation of gene expression but does not typically encode proteins directly. Thus, polypeptides are the primary focus of most genes, making this the correct answer.