Protein misfolding: prion disease: practice question

A Biochemistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Biochemistry · Protein misfolding: prion disease

Sample item

A 58-year-old woman has rapidly progressive dementia over 3 months with myoclonus. The EEG shows periodic sharp wave complexes. What is the molecular basis of this disease?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Conversion of alpha-helix-rich PrPc to a protease-resistant beta-sheet-rich PrPsc

Creutzfeldt-Jakob disease is a prion disorder in which the normal cellular prion protein is converted into a misfolded form rich in beta sheet that resists proteases and templates further conversion. No nucleic acid is involved. Brain histology shows spongiform change.

Option by option

  • A. Conversion of alpha-helix-rich PrPc to a protease-resistant beta-sheet-rich PrPsc (correct)

    Correct. A conformational change propagates in a templated manner without nucleic acid.

  • B. Integration of viral DNA into neuronal genes

    Prions contain no viral nucleic acid and there is no integration into the host genome.

  • C. Aggregation of alpha-synuclein into Lewy bodies

    Alpha-synuclein aggregates define Parkinson disease and Lewy body dementia.

  • D. Accumulation of hyperphosphorylated tau as neurofibrillary tangles

    Hyperphosphorylated tau tangles characterise Alzheimer disease, which is slower in course.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is A, Conversion of alpha-helix-rich PrPc to a protease-resistant beta-sheet-rich PrPsc. Creutzfeldt-Jakob disease is a prion disorder in which the normal cellular prion protein is converted into a misfolded form rich in beta sheet that resists proteases and templates further conversion.

Why is "Integration of viral DNA into neuronal genes" not the answer?

Prions contain no viral nucleic acid and there is no integration into the host genome.

Why is "Aggregation of alpha-synuclein into Lewy bodies" not the answer?

Alpha-synuclein aggregates define Parkinson disease and Lewy body dementia.

Why is "Accumulation of hyperphosphorylated tau as neurofibrillary tangles" not the answer?

Hyperphosphorylated tau tangles characterise Alzheimer disease, which is slower in course.

What concept does this question test?

It tests Protein misfolding: prion disease in Biochemistry. No nucleic acid is involved. Brain histology shows spongiform change.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Protein misfolding: prion disease?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.