Answer
During transcription, mRNA is created in the nucleus of a eukaryote.
Work Step by Step
Transcription occurs in the nucleus of a eukaryote. First, helicase unwinds the double helix by breaking the hydrogen bonds between the nitrogenous bases that hold the double helix together. Then, RNA polymerase matches complementary RNA base pairs using one of the DNA's strand as a template. It is important to notice that only one strand is being created, and this strand contains uracil instead of thymine.
