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

At any pH below the pI, the population of amino acids in solution with non-ionizable R-groups will have:

a net negative charge.

a net positive charge.

no charged groups.

no net charge.

positive and negative charges in equal concentrations.

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Verified step by step guidance

Understand the concept of isoelectric point (pI): The isoelectric point is the pH at which an amino acid has no net charge. At this pH, the positive and negative charges on the amino acid balance each other out.

Consider the structure of amino acids: Amino acids have at least two ionizable groups, the amino group (NH3+) and the carboxyl group (COO-). At different pH levels, these groups can gain or lose protons, affecting the overall charge of the amino acid.

Analyze the pH relative to the pI: At a pH below the pI, the environment is more acidic, meaning there are more protons (H+) available in the solution.

Determine the effect of low pH on amino acid charge: In an acidic environment (pH < pI), the carboxyl group (COO-) is more likely to gain a proton, becoming COOH, while the amino group remains protonated as NH3+. This results in a net positive charge on the amino acid.

Conclude the charge state: Since the carboxyl group is neutralized and the amino group remains positively charged, the amino acid will have a net positive charge at any pH below its pI.