Table of contents

1. Introduction to Biochemistry4h 34m
2. Water3h 23m
3. Amino Acids8h 10m
4. Protein Structure10h 4m
5. Protein Techniques14h 5m
6. Enzymes and Enzyme Kinetics13h 38m
7. Enzyme Inhibition and Regulation 8h 42m
8. Protein Function 9h 41m
9. Carbohydrates7h 49m
10. Lipids5h 49m
11. Biological Membranes and Transport 6h 37m
12. Biosignaling9h 45m
Review 1: Nucleic Acids, Lipids, & Membranes2h 47m
Review 2: Biosignaling, Glycolysis, Gluconeogenesis, & PP-Pathway3h 12m
Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism2h 26m
Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation1h 48m

1. Introduction to Biochemistry

Proteins

Biochemistry

1. Introduction to Biochemistry

Proteins

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Multiple Choice

This cartoon of the protein hormone insulin illustrates which aspects of insulin's structure?

The quaternary structure of hemoglobin

The sequence of nucleotides encoding insulin

The active site of an enzyme

The presence of two polypeptide chains linked by disulfide bonds

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Verified step by step guidance

Step 1: Begin by understanding the structural levels of proteins. Proteins have four levels of structure: primary (sequence of amino acids), secondary (local folding patterns like alpha-helices and beta-sheets), tertiary (three-dimensional folding of a single polypeptide chain), and quaternary (assembly of multiple polypeptide chains).

Step 2: Recognize that insulin is a protein hormone composed of two polypeptide chains, referred to as the A-chain and B-chain. These chains are linked together by disulfide bonds, which are covalent bonds formed between the sulfur atoms of cysteine residues.

Step 3: Disulfide bonds play a critical role in stabilizing the quaternary structure of proteins that consist of multiple polypeptide chains. In the case of insulin, these bonds ensure the proper assembly and functionality of the hormone.

Step 4: Compare the options provided in the question. The quaternary structure of hemoglobin refers to a different protein and is unrelated to insulin. The sequence of nucleotides encoding insulin pertains to the genetic information, not the structural aspect. The active site of an enzyme is a functional region, but insulin is not an enzyme.

Step 5: Conclude that the cartoon of insulin illustrates the presence of two polypeptide chains linked by disulfide bonds, which is a key feature of its quaternary structure.