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

3. Amino Acids

Amino Acid Groups

Biochemistry

3. Amino Acids

Amino Acid Groups

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Multiple Choice

Which of the following pairs of amino acids can form a salt bridge at physiological pH?

Serine and Threonine

Phenylalanine and Tyrosine

Glycine and Alanine

Aspartate and Lysine

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Verified step by step guidance

Understand the concept of a salt bridge: A salt bridge is a type of non-covalent interaction that occurs between oppositely charged amino acid side chains, typically at physiological pH (~7.4). This interaction is based on electrostatic attraction.

Identify the amino acid side chains that can carry charges at physiological pH: Acidic amino acids like Aspartate (Asp) and Glutamate (Glu) have negatively charged side chains due to their carboxyl groups. Basic amino acids like Lysine (Lys), Arginine (Arg), and Histidine (His) have positively charged side chains due to their amine groups.

Analyze the pairs of amino acids provided: Serine and Threonine have polar, uncharged side chains; Phenylalanine and Tyrosine have aromatic side chains, with Tyrosine being slightly polar; Glycine and Alanine have nonpolar side chains. None of these pairs can form a salt bridge because they lack oppositely charged side chains.

Focus on the pair Aspartate and Lysine: Aspartate has a negatively charged carboxyl group (-COO⁻) at physiological pH, and Lysine has a positively charged amine group (-NH₃⁺) at physiological pH. These oppositely charged groups can interact to form a salt bridge.

Conclude that Aspartate and Lysine are the correct pair to form a salt bridge at physiological pH due to their complementary charges and electrostatic attraction.