Step I DNA mutation review question

[DrPettans]

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A review question says that a point mutation in the DNA from this: "ATGCAA" to this: "ATGTAA", is a nonsense mutation (that is, a mutation where the new triplet codes for a STOP signal).

The explanation is: The sequence now contains TAA which will be transcribed to UAA in the mRNA.

I get it, UAA is a stop codon, while CAA, is not, and that is a nonsense mutation.

My question is:

how do I know if the stem cells gives me the TEMPLATE strand of DNA (so mRNA will be complementary and antiparallel, and also changing any T for U) or the ANTITEMPLATE strand of DNA (so mRNA would be just the same as the antitemplate, only changing any T for U). In this example, given the answers, it is the antitemplate strand, but how do I know? they don't say it.

 

[tvelocity514]

Did it give you 5' /3' ends? That's usually how you tell. According to Kaplan you are supposed to assume it's 5--> 3 if they don't give you anything else.


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[DrPettans]

yes that's always the way it's supposed to be written, but I don't know how to tell which of the strands they give, if they don't say.

 

[DrPettans]

or maybe as they always write in the 5 to 3 sense, it will always be the antitemplate strand unless they say specifically a different thing?