An amino acid is an amphoteric molecule.

Amino acids are organic compounds that combine to form proteins. Proteins are large biomolecules that consist of one or more long chains of amino acid residues.  Amino acids are the basic building blocks of proteins and serve as the nitrogenous backbones for compounds like neurotransmitters and hormones. Although over 500 amino acids exist in nature, only 22 α-amino acids are incorporated into proteins.  Proteins are present in all living organisms and include many essential biological compounds such as enzymes, hormones, and antibodies.  Here are some examples of amino acids: Lysine: An... Show more

Amino acids are organic compounds that combine to form proteins. Proteins are large biomolecules that consist of one or more long chains of amino acid residues. 

Amino acids are the basic building blocks of proteins and serve as the nitrogenous backbones for compounds like neurotransmitters and hormones. Although over 500 amino acids exist in nature, only 22 α-amino acids are incorporated into proteins. 
Proteins are present in all living organisms and include many essential biological compounds such as enzymes, hormones, and antibodies. 

Here are some examples of amino acids:
Lysine: An essential amino acid that is necessary for human health, but the body cannot make it.
Threonine: A part of tooth enamel, collagen, and elastin, so it is necessary for healthy skin and teeth. 

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