Answer:
Proteins range in molecular weight from 1000 to more than 1 million daltons (Da), but the folded size of a globular protein is not necessary correlated to its molecular weight. Proteins composed of about 250 amino acids or less often have a simple, compact globular shape. Larger globular proteins are usually made up of two or more recognizable and distinct structures, termed domains or modules. These are compact, folded protein structures that are usually stable by themselves in aqueous solution. Typical domain structures consist of hydrophobic cores with hydrophilic surfaces. Individual domains often possess unique functional behaviors and often perform unique functions within the larger protein in which they are found.