The number of groups present in a tripeptide Asp–Glu–Lys is ……….. . — Biomolecules Chemistry Question

💡 Solution & Explanation

**Step 1: Identify the structure of a tripeptide** A tripeptide contains 3 amino acids linked by 2 peptide bonds. The general structure is: H₂N–(AA₁)–CO–NH–(AA₂)–CO–NH–(AA₃)–COOH **Step 2: Count functional groups in the backbone** - 1 free amino group (–NH₂) at the N-terminus - 1 free carboxyl group (–COOH) at the C-terminus - Total from backbone: 2 groups **Step 3: Identify side chain groups** The three amino acids are: - Asp (aspartic acid): has –COOH in side chain - Glu (glutamic acid): has –COOH in side chain - Lys (lysine): has –NH₂ in side chain **Step 4: Count ionizable side chain groups** - Asp contributes: 1 carboxyl group - Glu contributes: 1 carboxyl group - Lys contributes: 1 amino group - Total from side chains: 3 groups **Step 5: Calculate total ionizable groups** Total = backbone groups + side chain groups Total = 2 + 3 = 5 Therefore, the answer is 5.00.