Answer:
Leucine, isoleucine and lysine are classified as essential amino acids.
Step-by-step explanation:
Amino acids are the important biomolecules in which an alpha-carbon is attached to a side chain R, two functional groups and one hydrogen.
The two functional groups are: amine group (-NH₂) and carboxyl group (-COOH).
There are total 21 amino acids in a human body. They can be divided into two types: Essential amino acids and Nonessential amino acids
Essential amino acids are the 9 amino acids that can not be produced by the human body and thus has to be taken through diet.
Example: leucine, isoleucine, lysine.
Therefore, leucine, isoleucine and lysine are classified as essential amino acids.