DNA polymerase removes the last few nucleotides synthesized whenever it stops. Enhancers can bind long distances from the start site of transcription. The transcriptional machinery requires a complex of general transcription factors. Each gene contains its own regulatory sequences. The polymerases must deal with chromatin structure.
All codons specify more than one amino acid.
The genetic code is redundant. All amino acids are specified by more than one codon. The genetic code is different in procaryotes and eucaryotes. All codons specify an amino acid. RNA splicing takes place in the cytoplasm.