Question

Imagine that an RNA polymerase is transcribing a segment of DNA that contains the following sequence:

5'-AGTCTAGGCACTGA-3'
3'-TCAGATCCGTGACT-5'
If the polymerase is transcribing from this segment of DNA from left to right, which strand (top or bottom) is the template?
What will be the sequence of that RNA?_______

Answer 1

The bottom strand (3'-TCAGATCCGTGACT-5') is the template strand for transcription, and the resulting RNA sequence would be 5'-AGUCUAGGCACUGA-3', with uracils replacing thymines.

Step-by-step explanation:

The template strand for transcription is the one that RNA polymerase reads in the 3' to 5' direction, and transcription proceeds by adding complementary RNA nucleotides to the growing RNA strand in the 5' to 3' direction. Given the DNA sequence 5'-AGTCTAGGCACTGA-3' and 3'-TCAGATCCGTGACT-5', and knowing that the polymerase transcribes from left to right as indicated, the bottom strand (3'-TCAGATCCGTGACT-5') will be the template strand.

As the template strand is read in the 3' to 5' direction, the RNA polymerase synthesizes the new RNA strand by adding nucleotides that are complementary to the template strand. However, in RNA, the base thymine (T) is replaced with uracil (U). Therefore, the RNA sequence will be 5'-AGUCUAGGCACUGA-3'.