Question

If mRNA is complementary to the DNA template strand and the DNA template strand is complementary to the DNA nontemplate strand, then why are base sequences of mRNA and the DNA nontemplate strand not identical? Could they ever be?

Answer 1

No

Step-by-step explanation:

Let me explain it to you:

DNA is a double chain. One is called coding strand, while the other is known as template strand (noncoding). During the process of transcription, template DNA strand is used to generate a de novo mRNA chain, whose sequence is identical by complementary to the coding strand.

If you have the sequence

Coding 5´AAAATTCG 3´

Noncoding 3´TTTTAAGC 5´

Using the noncoding sequence, by complementarity, the RNA polymerase is going to synthesize the following mRNA:

mRNA 5´AAAUUCG 3´

Which is equal to the sequence of the coding strand, but replacing Ts for Us.