Oncogenes and tumor suppressor genes

Oncogenes and tumor suppressor genes are classes of genes that code for various proteins that are involved in the progression of the cell cycle.

Oncogenes are actually mutated versions of proto-oncogenes, which are normal genes in charge of positive regulation of the cell-cycle.

So the protein products of proto-oncogenes stimulate cell growth and division - they’re like a gas pedal in a car.

Tumor suppressor genes, on the other hand, are in charge of negative regulation of the cell cycle, so their protein products stop its progression and promote apoptosis or cell death.

Tumor suppressor genes are involved in DNA repair mechanisms and inhibiting transcription factors that try to push the cell along in the cell cycle - so they’re like the brake pedal in a car.

Now, the cell cycle is the series of events that a cell goes through as it changes from being one cell into two daughter cells.

The cell cycle has two phases: interphase and mitosis. Interphase is comprised of the G1 phase, during which the cell grows and performs its cell functions, the S phase, during which DNA is replicated, and the G2 phase, during which the cell grows again before entering mitosis.

At the end of G1 and G2, there are cell cycle control points called the G1 and G2 checkpoints, where the cell checks to see if there’s any DNA damage.

The main control point is the G1 checkpoint.

If it turns out that there is DNA damage, then the cell can either enter a non-dividing state called the G0 phase, where the DNA repair mechanisms try to fix the problem, or the cell can self-destruct in a process called apoptosis.