DRAW IT The artificial sweetener aspartame, or NutraSweet®, is made by joining aspartic acid to methylated phenylalanine, as shown in the following.
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a. What types of molecules are aspartic acid and phenylalanine?
b. What direction is the hydrolysis reaction (left to right or right to left)?
c. What direction is the dehydration synthesis reaction?
d. Circle the atoms involved in the formation of water.
e. Identify the peptide bond.

Verified step by step guidance

1. Step 1: Identify the types of molecules - Aspartic acid and phenylalanine are both amino acids. Aspartic acid is an acidic amino acid, while phenylalanine is a nonpolar, aromatic amino acid.
2. Step 2: Determine the direction of the hydrolysis reaction - Hydrolysis involves breaking a bond with the addition of water, so it proceeds from right to left, breaking the peptide bond in aspartame.
3. Step 3: Determine the direction of the dehydration synthesis reaction - Dehydration synthesis involves forming a bond by removing water, so it proceeds from left to right, forming the peptide bond in aspartame.
4. Step 4: Identify the atoms involved in the formation of water - In dehydration synthesis, the hydroxyl group (OH) from aspartic acid and a hydrogen atom (H) from phenylalanine combine to form water (H2O).
5. Step 5: Identify the peptide bond - The peptide bond is the covalent bond formed between the carboxyl group of aspartic acid and the amino group of phenylalanine, resulting in the release of water.

Key Concepts

Amino Acids

Aspartic acid and phenylalanine are both amino acids, which are the building blocks of proteins. Amino acids consist of a central carbon atom bonded to an amino group, a carboxyl group, a hydrogen atom, and a variable R group that determines the specific properties of each amino acid. Aspartic acid is classified as a polar, negatively charged amino acid, while phenylalanine is a non-polar, aromatic amino acid. Understanding their structure and properties is essential for grasping how they combine to form proteins.

Hydrolysis and Dehydration Synthesis

Hydrolysis and dehydration synthesis are two fundamental biochemical reactions. Hydrolysis is the process of breaking down complex molecules into simpler ones by adding water, typically moving from right to left in a reaction. Conversely, dehydration synthesis (or condensation) involves the formation of larger molecules from smaller ones by removing water, usually moving from left to right. These reactions are crucial for understanding how biomolecules like proteins are formed and broken down.

Peptide Bonds

Peptide bonds are covalent bonds that link amino acids together to form proteins. They are formed during dehydration synthesis when the carboxyl group of one amino acid reacts with the amino group of another, releasing a molecule of water. Identifying peptide bonds is essential for understanding protein structure and function, as the sequence and arrangement of amino acids determine the protein's properties and biological activity.