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PCAT Biological Processes – mRNA Transcription From dsDNA

  • by Sam
  • Apr 19, 2018
  • PCAT Question of the Day

The mRNA transcribed from a dsDNA molecule has a partial sequence of 5′-AUGAAUC-3′. The corresponding sequence on the sense DNA strand is:

A. 3′-TACTTAG-5′.
B. 3′-UACUUAG-5′.
C. 5′-AUGAAUC-3′.
D. 5′-ATGAATC-3′.

Click for Explanation

D is correct. The sense (or coding) DNA strand should have the same sequence as the mRNA strand produced, except the DNA strand should contain thymine instead of uracil. Here, Choices B and C represent mRNA, not DNA, and Choice A is the sequence of the antisense (or template) DNA strand.

mRNA:                              5′-AUGAAUC-3′
antisense DNA:                 3′-TACTTAG-5′
sense DNA:                       5′-ATGAATC-3′

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