mRNA is synthesized in the nucleus using the nucleotide sequence of DNA as a template. The transcription process requires nucleotide triphosphates as substrates and is catalyzed by RNA polymerase II. During transcription, an ssDNA molecule is decoded by RNA polymerase and mRNA is synthesized in the nucleus. mRNA directly regulates the synthesis of proteins, which happens in the cytoplasm. mRNA is created in the nucleus where it is moved out and into the cytoplasm to attach to ribosomes.