Imagine you have a patient who is clearly suffering from a deficiency of a particular protein. Biochemical assays on blood and other tissues suggest the patient is producing considerably less of that protein than most people do, although production of all other proteins that were tested was normal. You check the dna sequence of the gene that makes that protein, and everything seems to be in order. Thinking about the types of nucleic acids we have in the human body, offer a plausible explanation for this. Imagine you are creating an organism that you are going to use to study the effects of living around undersea hot water vents on metabolism. The organism will inhabit an ecosystem where the average temperature is 400o: you are going to decide exactly what the sequence of this organism"s dna will be. Imagine you have an individual with a nonfunctional version of the histone acetyltransferase gene.