In the dipeptide shown below, which answer choice correctly identifies the location of the peptide bond?\[\text{Glycine} - \ce{NH2-CH2-COOH} + \text{Alanine} - \ce{NH2-CH(CH3)-COOH}\]A segment of the resulting dipeptide is:\[\ce{NH2-CH2-CO-NH-CH(CH3)-COOH}\]Which bond is the peptide bond?

• A. The bond between the alpha carbon of glycine and its amino group (\ce{CH2-NH2})
• B. The bond between the carboxyl group of alanine and its alpha carbon (\ce{COOH-CH(CH3)})
• C. The bond between the carbonyl carbon (C=O) of glycine and the nitrogen (N) of alanine (\ce{CO-NH})
• D. The bond between the methyl group of alanine and its alpha carbon (\ce{CH3-CH})

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the concept of a peptide bond. A peptide bond is a covalent bond formed between the carboxyl group (-COOH) of one amino acid and the amino group (-NH2) of another amino acid during a condensation reaction, releasing a molecule of water ( ext{H2O}).
2. Step 2: Analyze the structure of the dipeptide provided. The dipeptide is formed by glycine ( ext{NH2-CH2-COOH}) and alanine ( ext{NH2-CH(CH3)-COOH}). The resulting dipeptide structure is ext{NH2-CH2-CO-NH-CH(CH3)-COOH}.
3. Step 3: Locate the peptide bond in the dipeptide structure. The peptide bond is the ext{CO-NH} linkage formed between the carbonyl carbon (C=O) of glycine and the nitrogen (N) of alanine.
4. Step 4: Eliminate incorrect options. The bond between the alpha carbon of glycine and its amino group ( ext{CH2-NH2}) is not a peptide bond, as it is part of the glycine structure. Similarly, the bond between the carboxyl group of alanine and its alpha carbon ( ext{COOH-CH(CH3)}) and the bond between the methyl group of alanine and its alpha carbon ( ext{CH3-CH}) are structural bonds within alanine and not peptide bonds.
5. Step 5: Confirm the correct answer. The peptide bond is specifically the bond between the carbonyl carbon (C=O) of glycine and the nitrogen (N) of alanine ( ext{CO-NH}). This is the defining feature of a peptide bond in the dipeptide structure.