A protein is a long train of amino acids linked together. Proteins have different functions; they can provide structure (ligaments, fingernails, hair), help in digestion (stomach enzymes), aid in movement (muscles), and play a part in our ability to see (the lens of our eyes is pure crystalline protein).
Protein is a long chain molecule made up of amino acids joined by peptide bonds. Protein forms the structural material of bodily tissues.
Proteins, the principal constituents of the protoplasm of all cells, are of high molecular weight and consist essentially of combination of a amino acids in peptide linkages.
Twenty different amino acids are commonly found in proteins and each protein has a unique, genetically defined amino acid sequence which determines its specific shape and function.
They serve as enzymes, structural elements, hormones, immunoglobulins, etc. And are involved in oxygen transport, muscle contraction, electron transport and other activities throughout the body and in photosynthesis.