Cancer and uncontrolled cell division Transitional Reasoning Download PDF

Questions

1. 1.

   A laboratory researcher cultures two groups of mammalian epithelial cells in petri dishes supplied with limited growth factors: Group 1 consists of normal non-cancerous cells, while Group 2 consists of malignant carcinoma cells. Group 1 cells form a single uniform monolayer and halt division once adjacent cell surfaces touch, whereas Group 2 cells continue dividing, piling atop one another into disorganized multi-layered clusters. Which biological mechanism best accounts for the uncontrolled proliferation observed in the Group 2 cells under these experimental conditions?

   • A) Group 2 cells permanently arrest at the G2/M checkpoint to repair DNA before initiating cytokinesis.
   • B) Group 2 cells have lost density-dependent inhibition and can bypass the G1 checkpoint independent of external growth factor signals.
   • C) Group 2 cells rely strictly on anchoring to an extracellular matrix to activate cyclin-dependent kinase inhibitors.
   • D) Group 2 cells enter a reversible G0 resting state as soon as nutrient levels in the growth medium decrease.