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 accounts for the differences among the various amino acids?

The peptide bond between amino acids

The presence of a carboxyl group

The structure of the R group (side chain)

The presence of an amino group

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Verified step by step guidance

Understand that amino acids are the building blocks of proteins, and they share a common structure: a central carbon atom (α-carbon) bonded to an amino group (-NH₂), a carboxyl group (-COOH), a hydrogen atom, and a variable R group (side chain).

Recognize that the peptide bond is a covalent bond formed between the carboxyl group of one amino acid and the amino group of another during protein synthesis. However, this bond is the same for all amino acids and does not account for their differences.

Note that the carboxyl group (-COOH) and the amino group (-NH₂) are functional groups present in all amino acids, so they do not contribute to the variability among amino acids.

Focus on the R group (side chain), which is the only part of the amino acid structure that varies. The R group determines the chemical properties (e.g., polarity, charge, hydrophobicity) and the specific identity of each amino acid.

Conclude that the differences among the various amino acids are due to the structure of their R groups (side chains), which can range from a simple hydrogen atom (as in glycine) to more complex structures like aromatic rings or sulfur-containing groups.