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

4. Protein Structure

Protein Folding

Biochemistry

4. Protein Structure

Protein Folding

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Multiple Choice

For which reason are \( \alpha \)-helices and \( \beta \)-sheets common folding patterns in polypeptides?

They are stabilized by hydrogen bonds between backbone atoms.

They require the presence of disulfide bonds for stability.

They only occur in proteins with hydrophobic amino acids.

They are formed exclusively by interactions with water molecules.

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Verified step by step guidance

Understand the structural features of polypeptides: Polypeptides are chains of amino acids linked by peptide bonds. Their folding patterns, such as α-helices and β-sheets, are part of the secondary structure of proteins.

Recognize the role of hydrogen bonds: Both α-helices and β-sheets are stabilized by hydrogen bonds formed between the backbone atoms of the polypeptide chain. Specifically, these bonds occur between the carbonyl oxygen of one amino acid and the amide hydrogen of another.

Clarify why disulfide bonds are not required: Disulfide bonds are covalent bonds formed between the sulfur atoms of cysteine residues. While they contribute to the tertiary structure of proteins, they are not necessary for the formation of α-helices or β-sheets.

Address the hydrophobic amino acid misconception: Hydrophobic amino acids influence protein folding by driving the formation of the hydrophobic core in the tertiary structure, but they are not directly responsible for the formation of α-helices or β-sheets.

Explain the exclusion of water molecule interactions: While water molecules play a role in protein folding and stability, α-helices and β-sheets are formed primarily through intramolecular hydrogen bonding within the polypeptide backbone, not exclusively through interactions with water.