Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

30. Peptides and Proteins

Quaternary Protein Structure

Organic Chemistry

30. Peptides and Proteins

Quaternary Protein Structure

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Multiple Choice

Hemoglobin represents a commonly discussed tetramer that contains an even number of α and β subunits. Which of the following statements is true?

Hemoglobin must contain with 4 α subunits and 4 β subunits.

Hemoglobin must contain with 2 α subunits and 2 β subunits.

Hemoglobin contains R groups that only covalently bind to produce a quaternary structure.

Hemoglobin represents a multimeric protein with identical subunits.

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Verified step by step guidance

Understand the structure of hemoglobin: Hemoglobin is a tetramer, meaning it is composed of four subunits. These subunits are typically two alpha (α) and two beta (β) chains.

Evaluate the statement about the number of subunits: The statement 'Hemoglobin must contain with 4 α subunits and 4 β subunits' is incorrect because hemoglobin is composed of 2 α and 2 β subunits, not 4 of each.

Consider the quaternary structure: Hemoglobin's quaternary structure is stabilized by non-covalent interactions such as hydrogen bonds, ionic bonds, and hydrophobic interactions, rather than covalent bonds between R groups.

Assess the statement about identical subunits: Hemoglobin is not composed of identical subunits; it has two different types of subunits (α and β), making it a heterotetramer rather than a multimeric protein with identical subunits.

Conclude with the correct statement: The correct statement is 'Hemoglobin must contain with 2 α subunits and 2 β subunits,' which accurately describes the composition of hemoglobin.