MCAT Biology Question 14: Answer and Explanation

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Question: 14

14. In Alzheimer's disease, a protein called the amyloid precursor protein (APP) is cleaved to form a protein called β-amyloid. This protein has a β-pleated sheet structure and precipitates to form plaques in the brain. This mechanism of disease is most similar to which of the following pathogens?

  • A. Bacteria
  • B. Viruses
  • C. Prions
  • D. Viroids

Correct Answer: C

Explanation:

Prions are infectious proteins that cause misfolding of other proteins. Primarily, prions cause a shift toward β-pleated sheet confirmations, which leads to decreased solubility and degradability of proteins, ultimately leading to disease. This mechanism is very similar to the one described here for Alzheimer's disease, making choice (C) the correct answer.

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