Science Buddies: "Ask an Expert"

I am doing the project "From Genes to Genetic Diseases: What Kinds of Mutations Matter?"
In the procedure it gave an example of DNA changing to mRNA and is shows the change as:
DNA: GTG → ATG RNA: GUG → AUG
and instructs to just change the T's to U's. Why wouldn't I transcript the whole thing since it is mRNA so that it would be
RNA: CAC → UAC ??
Thanks.

I think you are doing this excellent project from this website:

https://www.sciencebuddies.org/science- ... #procedure

I’m not sure I understand your question, but in the example given, the mutation in the DNA is a change from CTC to ATG, so the mRNA changes from GUG to AUG. The change in the amino acid code from valine to methionine is non-pathogenic because both amino acids are neutral and nonpolar, so the structure of the protein would not be affected.

In your example, if the DNA code is CAC, then the m-RNA code would also be CAC and there would be no change in the amino acid in the protein. If the DNA had mutated from CAC to CAT, then the RNA code would be CAU instead of CAC, however, the amino acid would be not be changed since both sequences are codes for histidine.

Please do restate your question if I have not addressed your concern.

Donna