What is the difference between Tumour supressor genes and Oncogenes?

Tumour supressor genes (TSG) and oncogenes and the two main types of genes involved in cancer, however they are very different. TSG normally function to slow down cell division, repair DNA mistakes and cause apoptosis. When they do not function as they should cells divide uncontrollably resulting in the development of cancer. An example of a TSG is TP53, the gene that encodes the p53 protein.
Oncogenes are the abnormal version of proto-oncogenes. Proto-oncogenes enable cell growth. If they mutate or too many copies are created they become abnormal and enable uncontrollable cell growth which leads to cancer and are now refered to as oncogenes. An example of an oncogene is in the case of the philadelphia chromosome. A useful analogy to help remeber the role of TSG and oncogenes is to visualise the cell as a car. It has all the working parts such as brake pedals and accelerator pedals. You can imagine TSG as the brake pedals, slowing down the car and keeping it in check. You can imagine the protooncogenes as the acceleration pedal, keeping it moving at a healthy distance. Normal car (normal cell): brake pedal as TSG functioning normally and accelerator pedal as proto-oncogenes acting normally. However in an abnormal car (abnormal cell): the TSG arent functioning and the brake pedal is broken preventing the car from slowing. The oncogene accelerator pedal is stuck to the floor creating high uncontrolled speeds.