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

Previous problemNext problem

Struggling with Biochemistry?

Join thousands of students who trust us to help them ace their exams!Watch the first video

Multiple Choice

Which of the following amino acids contains a positively charged (basic) side chain at physiological pH?

Serine

Glutamine

Leucine

Lysine

Previous problemNext problem

Verified step by step guidance

Step 1: Understand the question. The problem asks which amino acid has a positively charged (basic) side chain at physiological pH (approximately 7.4). This requires knowledge of amino acid structures and their behavior at physiological pH.

Step 2: Recall the classification of amino acids. Amino acids can be grouped based on the properties of their side chains: polar, nonpolar, acidic, and basic. Basic amino acids have side chains that are positively charged at physiological pH.

Step 3: Analyze the given options. Serine has a polar, uncharged side chain (-CH2OH). Glutamine has a polar, uncharged side chain (-CH2CONH2). Leucine has a nonpolar, hydrophobic side chain (-CH2CH(CH3)2). None of these are basic.

Step 4: Examine Lysine. Lysine has a side chain containing an amino group (-CH2CH2CH2CH2NH2) that is protonated at physiological pH, making it positively charged and basic.

Step 5: Conclude that Lysine is the correct answer because its side chain is positively charged at physiological pH, unlike the other options provided.