RNA processing: spliceosome and anti-Sm antibody: 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 · RNA processing: spliceosome and anti-Sm antibody

Sample item

A 24-year-old woman has a malar rash, arthritis, proteinuria and positive antinuclear antibodies. Anti-Sm antibodies are present, a highly specific marker for her disease. What is the normal function of the antigen targeted?

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

The answer and the reasoning

B. Splicing of introns from pre-mRNA as part of small nuclear ribonucleoproteins

The Sm proteins are core components of small nuclear ribonucleoproteins (U1, U2, U4, U5, U6) that form the spliceosome and excise introns from pre-mRNA. Anti-Sm is highly specific for systemic lupus erythematosus. Anti-Jo-1 targets histidyl-tRNA synthetase in myositis, and anti-centromere antibody targets kinetochore proteins.

Option by option

  • A. Charging of transfer RNA with its amino acid

    Aminoacyl-tRNA synthetase is the target of anti-Jo-1 in myositis.

  • B. Splicing of introns from pre-mRNA as part of small nuclear ribonucleoproteins (correct)

    The Sm antigen is a spliceosome component.

  • C. Assembly of the kinetochore during mitosis

    Kinetochore proteins are the target of anti-centromere antibody in limited systemic sclerosis.

  • D. Unwinding of DNA at the replication fork

    Helicase is not the Sm antigen.

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.

More Biochemistry questions

Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is B, Splicing of introns from pre-mRNA as part of small nuclear ribonucleoproteins. The Sm proteins are core components of small nuclear ribonucleoproteins (U1, U2, U4, U5, U6) that form the spliceosome and excise introns from pre-mRNA.

Why is "Charging of transfer RNA with its amino acid" not the answer?

Aminoacyl-tRNA synthetase is the target of anti-Jo-1 in myositis.

Why is "Assembly of the kinetochore during mitosis" not the answer?

Kinetochore proteins are the target of anti-centromere antibody in limited systemic sclerosis.

Why is "Unwinding of DNA at the replication fork" not the answer?

Helicase is not the Sm antigen.

What concept does this question test?

It tests RNA processing: spliceosome and anti-Sm antibody in Biochemistry. Anti-Sm is highly specific for systemic lupus erythematosus. Anti-Jo-1 targets histidyl-tRNA synthetase in myositis, and anti-centromere antibody targets kinetochore proteins.

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 RNA processing: spliceosome and anti-Sm antibody?

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.