DNA and RNA Notations

For the most part, DNA and RNA notation is pretty straightforward. By convention, a string of nucleotides (DNA or RNA) will always be listed from 5′ to 3′. For instance, if GTCCAAT was listed in a passage, question, or answer choice the G would be the 5′ end and T the 3′ end.

For DNA the sense strand (i.e. the one that the mRNA product will end up looking like) is typically displayed unless notated by the question or passage

There are a variety of different names for the two strands of DNA during transcription keeping them straight can be pretty tricky. Understanding why the strands are called what they are makes it much easier. So let’s look at the variety of names they can have.  

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Description automatically generated

Non-Coding = Anti-sense = Minus (-) = Template 

In this case the mRNA product is the “code” that later goes on to create a protein via translation. Since it is complementary to the blue strand as seen below we call this the template strand as it served as the template from, which the mRNA is generated. 



We can also see that the sequence of the two strands read from 5′ to 3′ are not the same even if we consider Ts and Us identical. This makes the strand the non-coding strand because it doesn’t carry the mRNA code it only helps to create it. Anti-sense and minus (-) are essentially synonyms since it is lacking the code (minus) and because it isn’t the code it doesn’t make sense (anti-sense). 



Coding = Sense = Plus(+) = Non-template

The coding strand is therefore the exact opposite. Its sequence is the code in DNA form and as seen below is identical to the mRNA product with Ts and Us swapped between DNA and RNA respectively. Consequently, it receives the name coding strand and the various synonyms that go along with it. Plus (+) because it is plus the code and sense because its code makes sense.



However, this strand wasn’t used to generate the mRNA and therefore is called the non-template strand.