# DBT JRF 2020 — Question 48

Exam: DBT JRF 2020 · Section: A · Topic: Biochemistry · Difficulty: Medium

## Question

Which of the following is NOT a rational grouping of amino acids based on their polarity properties?

## Options

- **A.** Val and Leu
- **B.** Asn and Gln
- **C.** Glu and Ile
- **D.** Met and Leu

## Answer

Option C

## Explanation

Amino acid polarity groupings: Non-polar/hydrophobic: Gly (G), Ala (A), Val (V), Leu (L), Ile (I), Pro (P), Phe (F), Trp (W), Met (M). Polar uncharged: Ser (S), Thr (T), Cys (C), Asn (N), Gln (Q), Tyr (Y). Negatively charged: Asp (D), Glu (E). Positively charged: Lys (K), Arg (R), His (H). Grouping Glu (negatively charged/polar) with Ile (non-polar/hydrophobic) is IRRATIONAL — they have completely opposite polarities. The other pairs (Val+Leu = both non-polar; Asn+Gln = both polar uncharged amides; Met+Leu = both non-polar) share similar polarity properties.

Source: https://mypyqbuddy.com/questions/which-of-the-following-is-not-a-rational-6a05a8a02adafec470293216