Table of contents

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

18. Amino Acids and Proteins

Peptides

GOB Chemistry

18. Amino Acids and Proteins

Peptides

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1:16 minutes

Problem 17c

Textbook Question

Draw the structural formula for each of the following peptides:
c. His—Met—Gln

Verified step by step guidance

Identify the amino acids in the peptide: Histidine (His), Methionine (Met), and Glutamine (Gln). Each amino acid has a specific structure with an amino group (-NH₂), a carboxyl group (-COOH), and a unique side chain (R group).

Determine the order of the peptide chain: The sequence is His—Met—Gln, meaning Histidine is the N-terminal (starting amino acid), Methionine is in the middle, and Glutamine is the C-terminal (ending amino acid).

Connect the amino acids via peptide bonds: A peptide bond forms between the carboxyl group (-COOH) of one amino acid and the amino group (-NH₂) of the next amino acid. Remove a molecule of water (H₂O) during each bond formation.

Draw the backbone of the peptide: The backbone consists of repeating units of -NH-CH(R)-CO-, where R represents the side chain of each amino acid. For this peptide, include the side chains of Histidine (imidazole group), Methionine (thioether group), and Glutamine (amide group).

Add terminal groups: Ensure the N-terminal (Histidine) retains its free amino group (-NH₂) and the C-terminal (Glutamine) retains its free carboxyl group (-COOH). Double-check the structure for accuracy and completeness.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Peptide Structure

Peptides are short chains of amino acids linked by peptide bonds. Each amino acid has a specific structure consisting of an amino group, a carboxyl group, and a side chain (R group) that determines its properties. The sequence of amino acids in a peptide dictates its structure and function, making it essential to understand how to represent these connections in a structural formula.

Amino Acids

Amino acids are the building blocks of peptides and proteins, with 20 standard amino acids commonly found in nature. Each amino acid has a unique side chain that influences its chemical behavior and interactions. In the peptide His—Met—Gln, histidine (His), methionine (Met), and glutamine (Gln) are the specific amino acids that need to be represented in the structural formula.

Structural Formula Representation

The structural formula of a peptide visually represents the arrangement of atoms and the bonds between them. It typically shows the backbone of the peptide, which consists of repeating units of the amino group and carboxyl group, along with the side chains of the constituent amino acids. Understanding how to draw this representation is crucial for accurately depicting the peptide's structure.