What encodes the order of amino acids on a polypeptide chain?

The correct choice, which is mRNA, plays a crucial role in the process of translating genetic information into proteins. mRNA, or messenger RNA, is synthesized during transcription, where a specific segment of DNA is copied into RNA. This mRNA sequence is then used as a template during translation to determine the order of amino acids in a polypeptide chain, which ultimately folds into a functional protein.

Each group of three nucleotides in mRNA, known as a codon, corresponds to a specific amino acid. The ribosome reads these codons and, with the help of tRNA (transfer RNA), assembles the corresponding amino acids in the correct order to form the polypeptide chain. This precise encoding means that the sequence of nucleotides in mRNA directly dictates the sequence of amino acids, showcasing the fundamental relationship between nucleic acids and proteins in biology.

Understanding this connection is vital, as the process highlights how genetic information is expressed and how proteins are synthesized, which is central to biotechnology and molecular biology.