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

Summary of Protein Structure

GOB Chemistry

18. Amino Acids and Proteins

Summary of Protein Structure

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4:41 minutes

Problem 110b

Textbook Question

Insulin is a protein hormone that functions as two polypeptide chains whose amino acid sequences are as follows:
A chain: GIVEQCCTSICSLTQLENYCN
B chain: FVNQHLCGDHLVEALYLV CGERGFFYTPKT
b. Considering the amino acid sequences, suggest how these two polypeptide chains might be held together in an active insulin molecule.

Verified step by step guidance

Identify the types of interactions that can occur between amino acids in polypeptide chains. These include hydrogen bonds, ionic bonds, hydrophobic interactions, and disulfide bridges.

Examine the amino acid sequences of the A and B chains for cysteine (C) residues, as these can form disulfide bridges, which are covalent bonds that can link different parts of a protein or different polypeptide chains.

Note that the A chain contains cysteine residues at positions 6 and 20, and the B chain contains cysteine residues at positions 7 and 19.

Propose that disulfide bridges could form between cysteine residues in the A and B chains, specifically between A6 and B7, and A20 and B19, helping to stabilize the active insulin structure.

Consider other interactions such as hydrogen bonds and hydrophobic interactions that might also contribute to the overall stability and conformation of the insulin molecule.

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Key Concepts

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

Protein Structure

Proteins are composed of amino acids linked by peptide bonds, forming polypeptide chains. The structure of a protein is crucial for its function, and it typically exists in four levels: primary (amino acid sequence), secondary (local folding patterns), tertiary (overall 3D shape), and quaternary (assembly of multiple polypeptide chains). In the case of insulin, understanding how the A and B chains interact is essential for grasping its functionality.

Disulfide Bonds

Disulfide bonds are covalent linkages formed between the sulfur atoms of cysteine residues in proteins. These bonds play a critical role in stabilizing the three-dimensional structure of proteins, particularly in secreted proteins like insulin. In insulin, disulfide bonds between the A and B chains help maintain its active conformation, ensuring proper biological activity.

Protein Folding and Function

The process of protein folding is vital for the biological activity of proteins, as the specific shape of a protein determines its function. In insulin, the correct folding of the A and B chains, facilitated by interactions such as hydrogen bonds, hydrophobic interactions, and disulfide bonds, is necessary for its role in glucose regulation. Understanding how these chains come together provides insight into insulin's mechanism of action.

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Textbook Question

Determine whether each of the following statements describes the primary, secondary, tertiary, or quaternary structure of a protein.

b. Peptide bonds join amino acids in a polypeptide chain.

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Textbook Question

Determine whether each of the following statements describes the primary, secondary, tertiary, or quaternary structure of a protein.

d. Hydrogen bonding between amino acids in the same polypeptide gives a coiled shape to the protein.

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Textbook Question

Determine whether each of the following statements describes the primary, secondary, tertiary, or quaternary structure of a protein.

b. Hydrogen bonds form between adjacent segments of the backbone of the same protein to form a “folded-fan” structure.

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Textbook Question

Determine whether each of the following statements describes the primary, secondary, tertiary, or quaternary structure of a protein.

d. Amino acids react in a condensation reaction to form a peptide bond.

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Textbook Question

Explain how a protein is denatured by the following:

c. Organic solvents

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Textbook Question

For each of the conjugated proteins described, identify to which class of conjugated protein it belongs.

b. Ionized zinc is attached to this protein so the protein can function.

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Textbook Question

For each of the conjugated proteins described, identify to which class of conjugated protein it belongs.

c. Phosphate groups are attached to this protein.

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Textbook Question

What level of protein structure is determined by the following:

a. Peptide bonds between amino acids?

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