Final answer:
A protein that has been denatured loses its functional shape or native structure, which can affect its ability to function properly. This can occur due to changes in temperature, pH, or chemical exposure and might be reversible or irreversible.
Step-by-step explanation:
A protein that has been denatured is said to have lost its functional shape or native structure. Denaturation is the loss of the secondary, tertiary, and quaternary structures of proteins by a physical or chemical process while maintaining the primary structure mostly intact. This process can lead to a protein losing its ability to function properly, as the shape of a protein is critical to its function.
For example, the albumin protein in egg whites becomes denatured when exposed to heat during cooking, changing from a clear to an opaque white substance. This denaturation can be either reversible or irreversible depending on the conditions and the protein.