Multiple Choice
Which of the following would be an example of pH-based protein denaturation?
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18. Amino Acids and Proteins
Protein Denaturation
Multiple Choice
Which of the following statements is false?
A
Preparing a steak to medium rare is heat-induced protein denaturation.
B
Bacteria releasing lactic acid in milk is pH-based protein denaturation.
C
Histidine is susceptible to pH-induced protein denaturation.
D
Heavy metal ions form strong bonds to nonpolar residues.
Verified step by step guidance1
Step 1: Understand the concept of protein denaturation, which is the process where proteins lose their native structure due to external stress such as heat, pH changes, or chemical agents.
Step 2: Analyze the first statement: 'Preparing a steak to medium rare is heat-induced protein denaturation.' Heat causes proteins in meat to unfold and coagulate, which is a classic example of heat-induced denaturation. This statement is true.
Step 3: Analyze the second statement: 'Bacteria releasing lactic acid in milk is pH-based protein denaturation.' The lactic acid lowers the pH, causing proteins like casein to denature and precipitate. This is an example of pH-induced denaturation, so this statement is true.
Step 4: Analyze the third statement: 'Histidine is susceptible to pH-induced protein denaturation.' Histidine has an imidazole side chain that can gain or lose protons depending on pH, affecting protein structure. This statement is true.
Step 5: Analyze the fourth statement: 'Heavy metal ions form strong bonds to nonpolar residues.' Heavy metal ions typically bind to polar or charged residues (like cysteine or histidine), not nonpolar residues. Therefore, this statement is false.
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