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Biomolecules question

2019 · 12 Jan · Shift 1 · Q9
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Biomolecules question

2019 · 12 Jan · Shift 1 · Q9

JEE MainChemistryBiomoleculesMCQ+4 / −1
Among the following compounds most basic amino acid is -
  1. A
    Lysine
  2. B
    Asparagine
  3. C
    Histidine
  4. D
    Serine
View written solutionFree

Correct answer: A

  1. Identify what is being asked

We need to find the most basic amino acid among:

  • Lysine
  • Asparagine
  • Histidine
  • Serine

Amino acid basicity depends mainly on the presence of a basic side chain that can accept a proton.

  1. Examine each option

A. Lysine

Lysine has a side chain containing an extra amino group: −(CH2)4NH2-(CH_2)_4NH_2−(CH2​)4​NH2​ This terminal amino group is strongly basic and readily accepts a proton.

So, lysine is a strongly basic amino acid.

B. Asparagine

Asparagine has the side chain: −CH2CONH2-CH_2CONH_2−CH2​CONH2​ This is an amide group, which is essentially neutral and not strongly basic.

So, asparagine is not strongly basic.

C. Histidine

Histidine has an imidazole ring in its side chain. This ring is basic, but it is less basic than the extra amino group present in lysine.

So, histidine is basic, but less basic than lysine.

D. Serine

Serine has the side chain: −CH2OH-CH_2OH−CH2​OH This is a hydroxyl-containing side chain, which is neutral and not basic.

So, serine is not basic.

  1. Compare the basic amino acids

Among the given options, the basic amino acids are:

  • Lysine
  • Histidine

Lysine is more basic because its side-chain amino group is more strongly proton-accepting than the imidazole nitrogen of histidine.

Thus, the most basic amino acid is: Lysine\boxed{\text{Lysine}}Lysine​

  1. Evaluate options
  • A: Lysine — Correct
  • B: Asparagine — Incorrect
  • C: Histidine — Incorrect
  • D: Serine — Incorrect
  1. Comparison with stored correct answer

Stored correct answer: A

Our derived answer: A (Lysine)

They match.

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