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 statements about the 20 standard amino acids is correct?

They all contain both an amino group and a carboxyl group attached to the same carbon atom.

All 20 amino acids have nonpolar side chains.

They are all essential amino acids in humans.

Each amino acid contains a sulfur atom in its side chain.

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Verified step by step guidance

Step 1: Begin by understanding the structure of the 20 standard amino acids. Each amino acid has a central carbon atom (called the alpha carbon) to which four groups are attached: an amino group (-NH₂), a carboxyl group (-COOH), a hydrogen atom, and a unique side chain (R group). This structure is common to all 20 standard amino acids.

Step 2: Evaluate the first statement: 'They all contain both an amino group and a carboxyl group attached to the same carbon atom.' This is correct because the amino group and carboxyl group are both attached to the alpha carbon in all standard amino acids.

Step 3: Analyze the second statement: 'All 20 amino acids have nonpolar side chains.' This is incorrect because the side chains of amino acids vary widely in polarity. Some amino acids, like glycine and alanine, have nonpolar side chains, while others, like serine and glutamine, have polar side chains.

Step 4: Examine the third statement: 'They are all essential amino acids in humans.' This is incorrect because only 9 of the 20 standard amino acids are considered essential for humans, meaning they must be obtained through the diet. The remaining amino acids can be synthesized by the body.

Step 5: Assess the fourth statement: 'Each amino acid contains a sulfur atom in its side chain.' This is incorrect because only two amino acids, cysteine and methionine, contain sulfur atoms in their side chains. The other amino acids do not have sulfur in their side chains.