Sketch the tetrapeptide obtained from four molecules of the \(\alpha\) -amino acid glycine.

Glycine is an α-amino acid, which means it contains an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom (-H), and a side chain, all attached to a central α-carbon atom. The side chain of glycine is a single hydrogen atom, making it the simplest α-amino acid. The structure of glycine can be represented as: H2N-CH2-COOH.

A peptide bond is formed when the amino group of one amino acid molecule reacts with the carboxyl group of another amino acid molecule, releasing a water molecule. This is a condensation reaction that forms a covalent bond between two amino acids, creating a dipeptide. This process can be repeated multiple times, resulting in longer peptide chains.

To sketch the tetrapeptide formed by four molecules of glycine, we need to form three peptide bonds, which will connect the four glycine molecules in a linear chain. Here's the step-by-step process: 1. First glycine molecule: H2N-CH2-COOH 2. Second glycine molecule: H2N-CH2-COOH 3. Form first peptide bond: The amino group of the first glycine molecule reacts with the carboxyl group of the second glycine molecule, releasing a water molecule, and forming the peptide bond: H2N-CH2-CONH-CH2-COOH 4. Third glycine molecule: H2N-CH2-COOH 5. Form second peptide bond: The amino group of the dipeptide reacts with the carboxyl group of the third glycine molecule, forming another peptide bond: H2N-CH2-CONH-CH2-CONH-CH2-COOH 6. Fourth glycine molecule: H2N-CH2-COOH 7. Form third peptide bond: The amino group of the tripeptide reacts with the carboxyl group of the fourth glycine molecule, forming the final peptide bond and the tetrapeptide: H2N-CH2-CONH-CH2-CONH-CH2-CONH-CH2-COOH The resulting tetrapeptide is a linear chain of four glycine molecules connected by three peptide bonds, with the structure H2N-CH2-CONH-CH2-CONH-CH2-CONH-CH2-COOH.