Question

Which of the following statements are correct regarding amino acids?
A. They are substituted methanes.
B. Serine is an aromatic amino acid.
C. Valine is a neutral amino acid.
D. Lysine is an acidic amino acid.
Choose the correct answer from the options given below:

• A. C and D only
• B. A and C only
• C. B and C only
• D. A and B only

Hint:

Remember the classification: Acidic = Glutamic acid (A-G), Basic = Lysine/Arginine (B-L), Neutral = Valine (N-V).

Answer 1

The Correct Option is B

Amino acids are organic compounds containing an amino group and an acidic group as substituents on the same carbon (the alpha-carbon). The detailed analysis of the provided statements is as follows:
• Statement A is Correct: Amino acids are considered substituted methanes. There are four substituent groups occupying the four valency positions of the alpha-carbon: hydrogen, a carboxyl group, an amino group, and a variable R group.
• Statement B is Incorrect: Serine is not an aromatic amino acid; it is a hydroxylic amino acid because its R group is a hydroxy-methyl group ($-CH_2OH$). Examples of aromatic amino acids include Tyrosine, Phenylalanine, and Tryptophan.
• Statement C is Correct: Valine is classified as a neutral amino acid because it contains one amino group and one carboxyl group, and its R group (isopropyl) is non-polar.
• Statement D is Incorrect: Lysine is not an acidic amino acid; it is a basic amino acid because it has an extra amino group in its side chain. Glutamic acid and Aspartic acid are examples of acidic amino acids. Based on this evaluation, only statements A and C are correct.