What determines the primary structure of a protein?

The primary structure of a protein is defined by the specific sequence of amino acids that are linked together to form a polypeptide chain. This sequence is critical because it determines how the protein will fold and ultimately function. Each amino acid in the sequence is connected by peptide bonds, which create the backbone of the protein.

The order of these amino acids is dictated by the corresponding mRNA sequence, which is transcribed from the DNA. While the sequence of nucleotides in DNA does play an essential role in determining which amino acids are incorporated into the protein, it is the sequence of amino acids themselves that constitutes the primary structure.

Understanding the primary structure is fundamental because it serves as the blueprint for the protein's overall conformation and biological activity. Any alteration in this sequence can lead to significant changes in the protein's properties and function, which is relevant in various biological processes and diseases.