Transcription and Translation · USMLE Step 1

Which of the following best describes the template strand during transcription?

  1. The DNA strand whose sequence matches the mRNA, apart from T being U
  2. The DNA strand read as the base-pairing template by RNA polymerase
  3. The non-coding strand that is never transcribed during gene expression
  4. The strand complementary to the mRNA that stays fully double-stranded
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Correct answer: The DNA strand read as the base-pairing template by RNA polymerase

The template (antisense) strand is the one read by RNA polymerase in 3′→5′ direction to build a complementary RNA in 5′→3′ direction. The non-template (coding) strand has the same sequence as mRNA (with T→U).

Difficulty: Medium Question 17 of 22

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