Question
Mon April 20, 2015 By: Kb Aulakh

Which sequence of RNA is transcribed from a hypothetical sequence of DNA given below?
3'-ATGCATGCATGCATGC-5'
5'-TACGTACGTACGTACG-3'
Explain in detail.

Expert Reply
Sheetal Kolte
Mon April 20, 2015

In a DNA sequence, the strand which reads in the 5’-3’ direction is the coding strand which contains the genetic information to be transcribed. The other strand in the 3’-5’ direction is the template strand which is complementary to the coding strand.

If we take the template strand and build a new DNA strand on it, we would get an exact copy of the original DNA coding strand formed. RNA transcription occurs in a similar fashion. If we build an RNA strand on the template strand, we will get a copy of the information on the DNA coding strand - but with one important difference. In RNA, uracil (U) is used instead of thymine (T). 

With reference to our question, the given hypothetical sequence of DNA is as follows:

3'-ATGCATGCATGCATGC-5'

5'-TACGTACGTACGTACG-3'

It is known that the sequence of mRNA is same as the coding strand of DNA. However, in RNA, thymine is replaced by uracil.

Hence, the sequence of mRNA will be 5'-UACGUACGUACGUACG-3'.

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