Final answer:
The isoelectric point of a protein is the pH at which it has equal numbers of positive and negative charges, resulting in a neutral overall charge.
Step-by-step explanation:
The statement “At its isoelectric point, the charge on all molecules of a particular protein is 0” is incorrect because at the isoelectric point, the net charge of the protein is indeed 0, but individual amino acids within the protein may still have charges. The isoelectric point is the pH at which a protein has equal numbers of positive and negative charges, resulting in a neutral overall charge for the protein.
For example, if an amino acid has a positive charge at a pH above its isoelectric point, it will have a net positive charge. Similarly, if an amino acid has a negative charge at a pH below its isoelectric point, it will have a net negative charge.