. Biological order. Biology. THE FUNCTIONAL ORDER of the corepressor would act on the operator gene. When the in- ductive bacterium i+ is o + , the operator is sensitive to the repressor. When the repressor is present, the operator gene is in position stop, and the two structural genes z+ and v+ are "blocked" and do not OPERON regulating gene operator structural genes 0 + Y +. ^____^ enzynrie forming ~ ~ systems /3-galactosidase permease co-repressor lactose metabolism Figure 22. The Operon. The structural genes z+ and v"^ "manufacture," respectively, /3-galactosidase
. Biological order. Biology. THE FUNCTIONAL ORDER of the corepressor would act on the operator gene. When the in- ductive bacterium i+ is o + , the operator is sensitive to the repressor. When the repressor is present, the operator gene is in position stop, and the two structural genes z+ and v+ are "blocked" and do not OPERON regulating gene operator structural genes 0 + Y +. ^____^ enzynrie forming ~ ~ systems /3-galactosidase permease co-repressor lactose metabolism Figure 22. The Operon. The structural genes z+ and v"^ "manufacture," respectively, /3-galactosidase and /3-galactoside permease only in the absence of the repressor. The repressor is produced from an aporepressor synthesized by the gene i+ and a corepressor that is a product of metabolism of the energy source — glucose, for example. Lactose, the inducer, competes with the corepressor and prevents the forma- tion of the repressor. When no repressor is present, the operator gene o+ is in position go, and the structural genes are active. When a repressor is present, the operator gene is in position stop, and enzyme synthesis is repressed. produce the enzyme-forming system. W'hen the repressor is absent, the operator gene is in position go. There is a new problem now, and the question must be asked: How does the operator gene act? We have every reason to believe that the operator does not send messages to the cytoplasm. One hypothesis is that it acts by inducing a [57]. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lwoff, André, 1902-. Cambridge, M. I. T. Press
Size: 1542px × 1621px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectbiology
