21. The regulatory gene does not need to be in, adjacent to, or even near the operon to control it. 22. One may distinguish between " structural " genes encoding enzymes, and regulatory genes encoding proteins that affect gene expression. 23. Even a small difference in the activity of a high-level regulatory gene could produce significant effects in the developing animal. 24. In fact, xol-1 is often referred to in the literature as the master sex regulatory gene of C . elegans. 25. Regulatory genes can also be described as positive or negative regulators, based on the environmental conditions that surround the cell.26. Genes that flick on less often, such as interesting regulatory genes , are less likely to be picked up, Venter said. 27. If, at some point, a cell acquires a mutation that turns off a major regulatory gene , " voil?", cancer. 28. A small group of regulatory genes in the giraffe appear to be responsible for the animal's stature and associated circulatory adaptations. 29. Even slight alterations in those regulatory genes can give rise to a wide network of changes in the developmental processes they govern. 30. People with abnormal iron regulatory genes do not reduce their absorption of iron in response to increased iron levels in the body.
