When DNA functions as a gene, the first thing that is made is a single strand of messenger RNA (mRNA). Here's why:

* DNA is the blueprint: DNA contains the genetic code, like a recipe for making proteins.

* Transcription: The process of making mRNA from DNA is called transcription. It's like copying the recipe from the cookbook onto a separate sheet of paper.

* RNA polymerase: An enzyme called RNA polymerase reads the DNA sequence and builds a complementary mRNA strand. This mRNA strand carries the genetic information from the DNA to the ribosome.

* Translation: The mRNA then travels to the ribosome where the genetic code is translated into a protein.

So, to summarize: DNA → mRNA → protein