JEE Main 2020 · 5 September · morning · Single correct · +4 / −1
Which of the following is not an essential amino acid :
- (a) Valine
- (b) Leucine
- (c) Lysine
- (d) Tyrosine
Answer and solution
Answer (d) Tyrosine
Solution
Chemistry ma’am · 3 steps
Tyrosine is the odd one out: your body makes it from phenylalanine, so food does not have to supply it.
- What essential means. An essential amino acid is one the human body cannot synthesise, so it must come from the diet. A non-essential one can be made inside the body from other compounds.
Amino acid Made in the body? Type Valine No essential Leucine No essential Lysine No essential Tyrosine Yes, from phenylalanine non-essential - Why tyrosine. The body adds an -OH group to the benzene ring of phenylalanine, an essential amino acid, and this gives tyrosine. As long as the diet has enough phenylalanine, tyrosine does not need to be eaten.
- So. Valine, leucine and lysine are all essential. Tyrosine (d) is the one that is not essential.
The idea to keep. Learn the 10 essential amino acids as PVT TIM HALL: Phenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histidine, Arginine, Leucine, Lysine. Anything outside this list is non-essential.
Answer from the NTA final answer key. Solution by PrepWiser.