Transcription: trnas trnas match up to the sequence of nucleotides with the correct amino acid to be inserted into the protein that is encoded: matches up to the mrna, each trna brings along an enzymatically attached amino acid. Mrnas are synthesized from precursors that are found in the nucleus: method one. 30 minute pulse: very large rnas radioactive, found to be in nucleus, heterogenous nuclear rnas. Extract the rna and look to see where the radioactivity end up: method two. Wash out the radioactivity for three hours after the pulse. Found to be in cytoplasm: hnrnas processed into smaller rnas that are exported to the cytoplasm. Extract rna and look to see where the radioactivity end up. All eukaryotic mrna precursors are synthesized by rna polymerase ii: enzyme has many different subunits. Requires the activity of various general" transcription factors (gtfs: called general because their binding is required for transcription to initiate at many different promoters.