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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5:30 minutes

Problem 17b

Textbook Question

Draw the structural formula for each of the following peptides:
b. KCG

Verified step by step guidance

Identify the amino acids in the peptide sequence 'KCG'. The sequence represents lysine (K), cysteine (C), and glycine (G). Each amino acid has a specific structure: lysine has a side chain with an amino group, cysteine has a thiol (-SH) group, and glycine has a hydrogen atom as its side chain.

Understand the peptide bond formation. Peptide bonds are formed between the carboxyl group (-COOH) of one amino acid and the amino group (-NH2) of the next amino acid, releasing a molecule of water (H2O) in the process.

Draw the backbone of the peptide. Start with the N-terminal (amino group of lysine) and connect the amino acids in the order K-C-G. The backbone will consist of repeating units of -NH-CH(R)-CO-, where R represents the side chain of each amino acid.

Add the side chains to the backbone. For lysine (K), attach the side chain (-CH2-CH2-CH2-CH2-NH2) to the alpha carbon. For cysteine (C), attach the thiol group (-SH) to the alpha carbon. For glycine (G), the side chain is simply a hydrogen atom.

Ensure the structure is complete and correct. Verify that the N-terminal (lysine) has a free amino group (-NH2) and the C-terminal (glycine) has a free carboxyl group (-COOH). Double-check the connectivity and orientation of the peptide bonds and side chains.

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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. The structure of a peptide is determined by the sequence of its constituent amino acids, which influences its properties and functions. Understanding the basic structure of peptides is essential for drawing their structural formulas.

Amino Acids

Amino acids are the building blocks of peptides and proteins, each containing an amino group, a carboxyl group, and a unique side chain (R group). The specific sequence of amino acids in a peptide determines its identity and characteristics. In the case of the peptide KCG, the amino acids involved are lysine (K), cysteine (C), and glycine (G).

Structural Formula Representation

The structural formula of a peptide visually represents the arrangement of atoms and the bonds between them. It includes the backbone of the peptide, which consists of the repeating units of amino acids, and highlights the side chains. Accurately drawing the structural formula requires knowledge of how to depict peptide bonds and the orientation of the amino acids.