The gene that codifies the beta-galactosidase enzyme is part of the <em>lac</em> operon, which also contains two other genes that produce enzymes involved in the metabolization of lactose.
Between glucose and lactose, the bacteria will preferentially use glucose as an energy source. On the other hand, lactose is a dimer, and thus a series of enzymes are needed to process lactose before its use as an energy source.
If there is no lactose present, the genes contained inside this operon are turned off (the operon is repressed).
In an absence of lactose, Lac repressor binds to <em>lac</em> operator. And as a result of this binding, transcription of <em>lac</em> operon will be prevented. Hence all the above mentioned genes of the <em>lac </em>operon will be repressed or will be turned off.
Early settlers in the town of Dry Gulch drilled wells to pump as much water as they wanted from the single aquifer beneath the town. (An aquifer is an underground body of water.) As more people settled in Dry Gulch, the aquifer level fell and new wells had to be drilled deeper at higher cost.Residents of Dry Gulch have a private incentive to under use water because it is a scarce resource.
Each organ of the body produces pangenes which travel through the blood to the reproduction organs to be given to offspring. This is of course false as proven by scientists.
First, the zygote becomes a solid ball of cells. Then it becomes a hollow ball of cells called a blastocyst. Inside the uterus, the blastocyst implants in the wall of the uterus, where it develops into an embryo attached to a placenta and surrounded by fluid-filled membranes.
