Question

The side chain of ______ amino acid containing a sulphur atom
A. Leucine
B. Threonine
C. Methionine
D. Arginine

Answer 1

Amino acids are colourless, crystalline, water-soluble and aminated organic acid. It is a structural unit of protein. It is amphoteric and the amino group gives a basic property.

Complete step-by-step answer:
- Leucine: It is a neutral amino acid which has one carboxylic acid and one amino group. It is one of the most important amino acids in humans. It is important for metabolic functions and protein synthesis. It is a branched-chain amino acid.
- Threonine: It is also a neutral amino acid. It is used in the biosynthesis of protein. It is an amino acid which contains an alpha-amino group, a carboxylic group and a side chain containing a hydroxyl group which makes it polar and uncharged amino acid.
- Methionine: It is the most important amino acids in humans. It is a substrate of cysteine and taurine amino acids. The methionine is obtained from the S-adenosyl methionine which is mainly a donor of the methyl group. Methionine is the amino acid which contains sulphur in their side chain. It helps in the biosynthesis of protein.
- Arginine: It is the amino acid which is formed by the alpha-amino group, an alpha-carboxylic group and the side chain contains a 3-carbon aliphatic chain. It plays an important role in cell division, healing of wounds etc.
Hence, the correct answer is C.

Note: Tryptophan is the most complex amino acid which consists of the indole ring. Amino acids react with both the base and acid and can have both the charges.