Which one out of A - D given below correctly represents the structural formula of the basic amino acid? [figure]
- C
- D
- A
- B
Answer
(2) D
Solution
A basic amino acid has an extra amino group in its R group.
A: R group contains –COOH ⇒ glutamic acid (acidic amino acid).
B: R group contains –OH ⇒ serine (neutral amino acid).
C: no α-carbon bearing both –NH2 and –COOH ⇒ not an amino acid.
D: R group = -(CH2)4-NH2 (extra amino group) ⇒ lysine, a basic amino acid.
As per NCERT, based on the number of amino and carboxyl groups, there are acidic (e.g. glutamic acid), basic (lysine) and neutral (valine) amino acids.
Answer: (2)