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.
Transcription of the lac operon is down-regulated through the binding of the lac repressor to the operator. In the absence of lactose, the repressor remains bound to the operator and preventing access of the RNA polymerase to the promoter. Transcription is blocked and the operon is repressed.