# Should I consider one or two DNA chains to find how many nucleotides are in a gene?

I am trying to solve an exercise.

How many nucleotides does a gene contain if information about 287 amino acids is encoded in it? What is the molecular mass and length of this gene?

AFAIK, I have to consider two DNA chains to find molecular mass, and one DNA chain to find the length of the gene (am I right here?).

But I am stuck trying to find how many nucleotides are there in a gene. Should I consider both or only one DNA chain? I suppose that both (as for the molecular mass of the gene) but I am not totally sure.

• This is a bad question from two perspectives. First, counting either one or two strands are equally correct or incorrect as there is nothing in the definition of a gene that specifies strandedness ( or even DNA). Second, the length of a gene is always longer than the DNA needed to encode the amino acids. All mRNAs have 3' and 5' non-coding regions of varying length, and, of course, there is always a stop codon. I approve of making students do calculations. I disapprove of questions that are biologically stupid. Dec 14, 2020 at 16:46
• @David, thank you very much for your reply. I agree with you. But this is exactly the question asked by my school teacher. Actually, these nuances are why I got stuck with this exercise. Dec 14, 2020 at 16:57
• Only your teacher can decide what the "right answer" is to their poorly thought out question. Either consult with them directly to find out what they want or give multiple answers and state clearly what assumptions you are making for each answer. Something like "If I assume that the gene only consists of an open reading frame and is single stranded then my answer is ###. However, if it is double stranded then my answer is #### etc." This has the advantage that you might be able to teach them ... Dec 14, 2020 at 18:46
• @tyersome, thank you for the advice. I have written exactly that way) Dec 14, 2020 at 19:13