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

Alpha Helix Disruption

Biochemistry

4. Protein Structure

Alpha Helix Disruption

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Multiple Choice

An α-helix would be destabilized most by:

DNA missense mutation leading to a Gly residue placed in the α-helix sequence.

Interactions between neighboring Asp & Arg residues.

A hydrophobic environment competing for hydrogen bonds.

DNA missense mutation leading to a Pro residue placed in the α-helix sequence.

A net electric dipole spanning several peptide bonds throughout the α-helix.

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Verified step by step guidance

Understand the structure of an α-helix: It is a common secondary structure in proteins characterized by a right-handed coil where each backbone N-H group forms a hydrogen bond with the C=O group of the amino acid four residues earlier.

Consider the role of amino acids in α-helix stability: Certain amino acids, like proline, can disrupt the α-helix due to their unique structure. Proline lacks a hydrogen atom on its nitrogen, preventing it from participating in hydrogen bonding, and its rigid ring structure introduces a kink in the helix.

Evaluate the impact of a DNA missense mutation: A missense mutation can lead to the substitution of one amino acid for another in the protein sequence. If proline is introduced into an α-helix, it can destabilize the helix due to its structural constraints.

Analyze the effects of neighboring Asp and Arg residues: These residues can form salt bridges, which might stabilize the α-helix rather than destabilize it, unless they are positioned in a way that disrupts the helix's regular structure.

Consider environmental factors: A hydrophobic environment might compete for hydrogen bonds, but the introduction of proline directly into the helix sequence is more disruptive due to its inability to maintain the regular hydrogen bonding pattern necessary for α-helix stability.