8Operon turned off (lactose is absent): OPERON Regulatory gene Figure 11.1B_1Operon turned off (lactose is absent):OPERONRegulatory genePromoterOperatorLactose-utilization genesDNAmRNARNA polymerase cannot attach to the promoterProteinActive repressorFigure 11.1B_1 The lac operon (part 1)
9Operon turned on (lactose inactivates the repressor): Figure 11.1B_2Operon turned on (lactose inactivates the repressor):DNARNA polymerase is bound to the promotermRNATranslationProteinFigure 11.1B_2 The lac operon (part 2)Inactive repressorLactoseEnzymes for lactose utilization
11lac operon trp operon DNA Active repressor Active repressor Tryptophan Figure 11.1Clac operontrp operonPromoterOperatorGeneDNAActive repressorActive repressorTryptophanFigure 11.1C Two types of repressor-controlled operonsInactive repressorInactive repressorLactose
19Cell division and random X chromosome inactivation Figure 11.2BEarly EmbryoAdultTwo cell populationsCell division and random X chromosome inactivationX chromo- somesActive XOrange furInactive XFigure 11.2B A tortoiseshell pattern on a female cat, a result of X chromosome inactivationAllele for orange furInactive XAllele for black furActive XBlack fur
27Root cells cultured in growth medium Cell division in culture Plantlet Figure 11.12Root of carrot plantSingle cellFigure Growth of a carrot plant from a differentiated root cellRoot cells cultured in growth mediumCell division in culturePlantletAdult plant
30The nucleus is removed from an egg cell. Figure 11.13_1Donor cellNucleus fromthe donor cellBlastocystThe nucleus is removed from an egg cell.A somatic cell from an adult donor is added.The cell grows in culture to produce an early embryo (blastocyst).Figure 11.13_1 Nuclear transplantation for cloning (part 1)
31The blastocyst is implanted in a surrogate mother. Figure 11.13_2Reproductive cloningBlastocystThe blastocyst is implanted in a surrogate mother.A clone of the donor is born.Therapeutic cloningFigure 11.13_2 Nuclear transplantation for cloning (part 2)Embryonic stem cells are removed from the blastocyst and grown in culture.The stem cells are induced to form specialized cells.
37Adult stem cells in bone marrow Figure 11.15Blood cellsAdult stem cells in bone marrowNerve cellsCultured embryonic stem cellsFigure Differentiation of stem cells in cultureHeart muscle cellsDifferent culture conditionsDifferent types of differentiated cells