Using the gas pedal analogy, the proto-oncogene would be an accelerator since they promote cell division and
deregulate apoptosis, while tumor suppressor would
be the brakes since they constrain the progress of the cell
cycle and induce cell apoptosis. An
oncogene is, therefore, when the accelerator
is stuck in down position and the brakes are not working.
There is a valve at the meeting point between each ureter and the bladder prevents the back flow of urine from the urinary bladder to the kidney
Photosynthesis, in the chloroplasts of the cells