Transcription of a gene squence

Question

5’ A.G.G.T.T.A.G.A.G.C.C.A.G.G.T.A.C 3’

3’ T.C.C.A.A.T.C.T.C.G.G.T.C.C.A.T.G 5’



What is the sequence of the pre-mRNA that would be produced from the gene sequence above?

Using the standard notation of letters to represent the bases in the pre-mRNA molecule.

Answer 1

DNA:

Coding strand:

5’ A.G.G.T.T.A.G.A.G.C.C.A.G.G.T.A.C 3’

Template strand:

3’ T.C.C.A.A.T.C.T.C.G.G.T.C.C.A.T.G 5’

Pre-mRNA:

5' A.G.G.U.U.A.G.A.G.C.C.A.G.G.U.A.C 3'



You must know two things in order to do this problem:

1. mRNA is transcribed 5' -> 3' direction
2. In mRNA, there are no T's so they are replaced with U's
3. This means that, if there is an A in the DNA strand, the RNA strand will have a U pair with it instead of a T.

To start this problem, you have to choose which strand you want to se to make the mRNA (if you are not told which one to use). Then, starting on the 3' end of the DNA strand you begin to create the mRNA strand with the correct base pair matches.

This is a good image of this process (you may have to copy and paste link in new tab):

https://cdn.kastatic.org/ka-perseus-images/1da89713b9aa8067742244d916749e72561bb3cc.png