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

Isoelectric Point

Biochemistry

3. Amino Acids

Isoelectric Point

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Multiple Choice

Which of the following amino acids has the highest isoelectric point (pI)?

Arginine

Glutamine

Aspartic acid

Tyrosine

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Verified step by step guidance

Step 1: Understand the concept of isoelectric point (pI). The isoelectric point is the pH at which an amino acid has no net electrical charge, meaning the positive and negative charges balance each other. This depends on the ionizable groups in the amino acid's structure.

Step 2: Analyze the amino acids provided in the question. Each amino acid has different ionizable groups that contribute to its pI. For example, Arginine has a positively charged guanidinium group, Aspartic acid has a negatively charged carboxyl group, Tyrosine has a phenolic group, and Glutamine has an amide group.

Step 3: Recall the typical pI values for amino acids. Basic amino acids like Arginine generally have higher pI values because their side chains are positively charged at physiological pH. Acidic amino acids like Aspartic acid have lower pI values due to their negatively charged side chains. Neutral amino acids like Glutamine and Tyrosine have intermediate pI values.

Step 4: Compare the structures and ionizable groups of the amino acids. Arginine has a basic side chain, which contributes to a higher pI. Aspartic acid has an acidic side chain, leading to a lower pI. Tyrosine has a phenolic group, which is less acidic than Aspartic acid but still contributes to a moderate pI. Glutamine has an amide group, which does not ionize significantly, resulting in a neutral pI.

Step 5: Conclude that Arginine has the highest isoelectric point among the given amino acids due to its basic guanidinium group, which raises its pI value significantly compared to the others.