Carbohydrate macromolecules (polysaccharides) are formed from polymers of monosaccharides. Nucleic acids then are polymeric macromolecules assembled from nucleotides, the monomer-units of nucleic acids. Saliva is made of chemicals, such as organic molecules, inorganic ions and macromolecules. Structural biology is concerned with the biomolecular structure of macromolecules, particularly proteins and nucleic acids. Many macromolecules, such as proteins or nucleic acids, form dimers. Mitochondria are organelles that synthesize ATP for the cell by metabolizing carbon-based macromolecules. Compounds that make up organisms may be divided into macromolecules and other, smaller molecules. Moist heat causes the destruction of microorganisms by denaturation of macromolecules, primarily proteins. Some of the largest molecules are macromolecules or supermolecules. Isotactic polymers are composed of isotactic macromolecules (IUPAC definition). Examples of nutrient uptake include that of metals, nitrogen, and macromolecules such as peptides. The individual macromolecules are not covalently linked. Redox signaling also includes active modulation of electronic flows in semiconductive biological macromolecules. Supramolecular chemistry is a field concerned with non-covalent interactions between macromolecules. X-ray crystallography of proteins and other macromolecules (PX or MX) are routinely performed.