Most of today’s somatic engineering uses viral vectors to transfer a transgene into target cells. Unfortunately, the vectors insert transgenes at random sites within the receiving chromosome. The outcome is necessarily somewhat unpredictable because genes are affected by their immediate environment, which in this case is not well defined. Also, a transgene might cause serious side effects if it were placed in the middle of an important existing gene. A human artificial chromosome (short HAC) is a microchromosome that can act as a new chromosome in a population of human cells. That is, instead of 46 chromosomes, the cell could have 47 with the 47th being very small, roughly 6-10 megabase in size, and able to carry new genes introduced by human researchers.1. If we transfer an insulin gene into patient’s pancreas for gene therapy, we call the insulin gene a ______ .2. The therapy may not be predictable because (a) ______ 3. and (b)______ 4. HACs can be used by______ .5. One megabase is equal to ______ kelobases.