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 amino acids is correct?

Amino acids with nonpolar side chains are always charged at physiological pH.

Glycine is the only amino acid with a chiral alpha carbon.

All amino acids contain a sulfur atom in their side chain.

All amino acids found in proteins are L-isomers.

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Verified step by step guidance

Step 1: Understand the structure of amino acids. Amino acids are the building blocks of proteins and consist of a central alpha carbon bonded to four groups: an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a unique side chain (R group).

Step 2: Analyze the first statement: 'Amino acids with nonpolar side chains are always charged at physiological pH.' Nonpolar side chains are hydrophobic and do not ionize, so they are not charged at physiological pH (~7.4). This statement is incorrect.

Step 3: Analyze the second statement: 'Glycine is the only amino acid with a chiral alpha carbon.' Glycine is unique because its side chain is a hydrogen atom, making it achiral (not chiral). Most other amino acids have a chiral alpha carbon. This statement is incorrect.

Step 4: Analyze the third statement: 'All amino acids contain a sulfur atom in their side chain.' Only two amino acids, cysteine and methionine, contain sulfur in their side chains. This statement is incorrect.

Step 5: Analyze the fourth statement: 'All amino acids found in proteins are L-isomers.' Amino acids in proteins are exclusively L-isomers, as opposed to D-isomers, which are not used in protein synthesis. This statement is correct.