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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0:59 minutes

Problem 65b

Textbook Question

Consider the amino acids glycine, proline, and lysine.
b. Using three-letter abbreviations for the amino acids, give the sequence for each of the possible tripeptides.

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Identify the three amino acids given in the problem: glycine (Gly), proline (Pro), and lysine (Lys). These are the building blocks for the tripeptides.

Understand that a tripeptide is a sequence of three amino acids linked together by peptide bonds. The order of the amino acids in the sequence matters, so each unique arrangement represents a different tripeptide.

Determine the total number of possible sequences. Since there are three amino acids and each position in the tripeptide can be occupied by any of the three amino acids, the number of permutations is calculated as 3! (3 factorial), which equals 6.

List all possible sequences using the three-letter abbreviations for the amino acids. The sequences are: Gly-Pro-Lys, Gly-Lys-Pro, Pro-Gly-Lys, Pro-Lys-Gly, Lys-Gly-Pro, and Lys-Pro-Gly.

Verify that all six sequences are unique and that no sequence is repeated. This ensures that all possible tripeptides have been accounted for.

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Key Concepts

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

Amino Acids

Amino acids are organic compounds that serve as the building blocks of proteins. Each amino acid has a specific structure, consisting of a central carbon atom, an amino group, a carboxyl group, a hydrogen atom, and a variable side chain (R group) that determines its properties. Glycine (Gly), proline (Pro), and lysine (Lys) are three distinct amino acids, each with unique characteristics that influence protein structure and function.

Tripeptides

Tripeptides are molecules formed by the linkage of three amino acids through peptide bonds. The sequence in which the amino acids are arranged is crucial, as it determines the tripeptide's properties and biological function. The order of amino acids can vary, leading to different tripeptides even if the same amino acids are used, highlighting the importance of sequence in protein chemistry.

Three-Letter Abbreviations

Three-letter abbreviations are standardized codes used to represent amino acids in a concise manner. For example, glycine is abbreviated as 'Gly', proline as 'Pro', and lysine as 'Lys'. These abbreviations facilitate easier communication and notation in biochemistry, especially when discussing sequences of amino acids in proteins or peptides.

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Peptides isolated from rapeseed that may lower blood pressure have the following sequence of amino acids. Draw the structure for each peptide and write the one-letter abbreviations.

a. Arg–Ile–Tyr

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Textbook Question

Peptides from sweet potato with antioxidant properties have the following sequence of amino acids. Draw the structure for each peptide and write the one-letter abbreviations.

b. Asn–Tyr–Asp–Glu–Tyr

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Textbook Question

Write the products for the following condensation or hydrolysis reactions:

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Textbook Question

Consider the following tripeptide:

a. Circle the N-terminal amino acid, and give its name. Draw a square around the C-terminal amino acid, and give its name.

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