Re:The DNA code is universal (Score 1)

The code might be (well, is) universal, but the control of what is translated at any given time is not. If you put human genome into a plant cell, you definitely won't produce a human, because cytoplasmic determinants that are present in human eggs are required to make sense of it all. Strict regulation of genes is crucial to the correct development of an organism, and the regulatory factors tend to be species-specific. Other stuff that has been mentioned (methylation, unique structure of genes, etc) also make things difficult.