Takes place in he nucleus; mRNA is made from a DNA strand (leading strand) the DNA is unzipped by helicase and RNA polymerase attaches to the DNA and nucleotides (uracil, adenine, cytosine, guanine) when it is done, mRNA is immature it gets a cap of 7' methylguanosine and a tail of 150-200 adenines and the introns are cut out and exons remain and it goes out of the nucleus.