What do mutations have to with amino acid changes in a protein?

Amino acid changes results in non-functional or different type of proteins because protein is a polymer of amino acids.

Explanation:

Mutations refers to changes in the genetic structure of organisms. It has everything to do with amino acid changes in a protein because proteins are important for gene expression.

Amino acids make up proteins. Specific amino acid sequence results in specific type of protein. Hence, a change in the sequence of amino acids that make up a particular protein might result either in non-functional protein or different type of protein.

Non-functional or different type of protein might have serious consequences for gene expression. For example, in human, sickle cell anemia results from the substitution of a single amino acid known as glutamic acid by valine.