Proteins are large biomolecules consisting of one or more long chains of amino acid residues linked by peptide bonds. They perform a vast array of functions within organisms, including catalyzing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules. In food science, proteins from sources like meat, eggs, dairy, and plants contribute to nutrition, texture, and functionality. Due to their polymeric nature, they lack fixed physical constants such as boiling or melting points, instead undergoing denaturation at elevated temperatures. Solubility varies widely depending on the specific protein sequence, pH, and ionic strength.