Table of contents

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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 of the following best describes the side chain of arginine at a pH of 11?

It is positively charged due to the protonated guanidinium group.

It is hydrophobic and uncharged at this pH.

It is negatively charged due to loss of a proton from the side chain.

It is neutral because the guanidinium group is deprotonated.

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Verified step by step guidance

Understand the structure of arginine: Arginine is an amino acid with a side chain containing a guanidinium group, which is highly basic and typically protonated at physiological pH.

Review the concept of pH and its effect on ionizable groups: At a pH of 11, the environment is alkaline, meaning fewer protons (H⁺) are available compared to physiological pH.

Determine the pKa of the guanidinium group: The guanidinium group of arginine has a pKa around 12.5, which means it remains protonated and positively charged at pH values below its pKa.

Analyze the pH relative to the pKa: Since the pH of 11 is below the pKa of 12.5, the guanidinium group will still retain its proton and remain positively charged.

Conclude the behavior of the side chain: At pH 11, the guanidinium group of arginine is positively charged due to its protonated state, and the side chain is not hydrophobic or negatively charged.