Question

Which of the following is an essential amino acid?

• A. Cystine
• B. Glycine
• C. Phenylalanine
• D. Serine

Answer 1

The correct option is C Phenylalanine

Amino acids are the monomers of proteins.
Those amino acids which cannot be made by the body are called essential amino acids. Phenylalanine is an example of essential amino acid.
Non-essential amino acids are those that can be synthesised in our body. Cysteine, glycine and serine are non-essential amino acids.

$\begin{array}{cc}\text{Essential amino acids}& \text{Non-essential amino acids}\\ \text{Threonine}& \text{Alanine}\\ \text{Histidine}& \text{Aspartic acid}\\ \text{Tryptophan}& \text{Glycine}\\ \text{Methionine}& \text{Asparagine}\\ \text{Phenylalanine}& \text{Serine}\\ \text{Lysine}& \text{Proline}\\ \text{Valine}& \text{Glutamic acid}\\ \text{Leucine}& \text{Arginine}\\ \text{Isoleucine}& \text{Glutamine}\\ & \text{Cysteine}\\ & \text{Tyrosine}\end{array}$