REPRODUCTIVE HABITS. The bull shark is viviparous, and the age to reach sexual maturity depends on the geographic region in which it is located but usually the age is ten years old for males and 10.9 years old for females. Some individuals can mature when reaching eight years of age. Mating occurs in late spring and the summer.
lac operon (lactose operon) is an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. Although glucose is the preferred carbon source for most bacteria, the lac operon allows for the effective digestion of lactose when glucose is not available.n this case, when lactose is required as a sugar source for the bacterium, the three genes of the lac operon can be expressed and their subsequent proteins translated: lacZ, lacY, and lacA.
The Trp operon in E. coli is turned on by default. The lac operon in E. coli is turned off when lactose is not present. A repressor binds to the operator and prevents RNA polymerase from binding to the promoter. When allolactose (closely related to lactose) is present, it binds to the repressor and prevents the repressor from binding. In this way, the presence of lactose allows the operon to be turned on to express the genes need to use lactose.