In aqueous acid solution, an amino acid zwitterion can lose a proton

The isoelectric point is the pH at which the amount of positive charge on an amino acid ------ the amount of negative charge

Amino acids are ------.

Amino acids are ------. 

------ are formed in the body but not in sufficient amount for body requirements especially in children.

------ is a major component of bones, muscles, and tendons

------ is components of hair, horns, hooves, feathers, fur, and the tough outer layer of skin.

Proteins are ------.

Oligopeptide contains ------ amino acid residues

Peptides and proteins are polymers of amino acids linked together by ------formed.