Question

The product of the retinoblastoma gene is a protein that binds to and inhibits the activity of a transcription factor that induces the expression of genes required for the cell to synthesize DNA. Briefly explain how a mutation in the retinoblastoma gene may promote cancer.

Answer 1

By definition, cancer is an uncontrolled division occurring in cells resulting in a mass of cells called tumours.
The first point to note is when an why does a cell divide?
A normal cell of the human body has a specific nuclear-cytoplasmic ratio. (Also called N/C ratio) When this ratio is high, the cell divides.
Retinoblastoma gene is responsible for curbing the synthesis of DNA by producing a protein that binds and inhibits the transcription factor that induces the expression of genes required for the cell to synthesize DNA. In short, it stops the transition of a cell from G₁ phase to the S phase.
If this gene is mutated, there will be an uncontrolled synthesis of DNA and subsequent uncontrolled proliferation of cells resulting in Cancer.
?