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 Configuration

Biochemistry

3. Amino Acids

Amino Acid Configuration

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Multiple Choice

Which part of an amino acid is always acidic?

The amino group (–NH₂)

The carboxyl group (–COOH)

The hydrogen atom attached to the alpha carbon

The side chain (R group)

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Verified step by step guidance

Understand the structure of an amino acid: Amino acids consist of a central alpha carbon bonded to four groups: an amino group (–NH₂), a carboxyl group (–COOH), a hydrogen atom, and a variable side chain (R group).

Recall the chemical properties of the carboxyl group (–COOH): The carboxyl group contains a hydroxyl (-OH) attached to a carbonyl (-C=O). It is acidic because it can donate a proton (H⁺) to the surrounding environment, forming a carboxylate ion (–COO⁻).

Compare the amino group (–NH₂): The amino group is basic, not acidic, because it can accept a proton (H⁺) to form –NH₃⁺.

Evaluate the hydrogen atom attached to the alpha carbon: This hydrogen atom is neutral and does not exhibit acidic or basic properties.

Analyze the side chain (R group): The acidity or basicity of the side chain depends on its specific chemical structure, but it is not universally acidic across all amino acids. Therefore, the carboxyl group (–COOH) is the part of an amino acid that is always acidic.