Q.How is a cancerous cell different from a normal cell?

Cancerous cells differ from normal cells in that they divide uncontrollably (losing contact inhibition and the ability to stop dividing), fail to differentiate properly, do not undergo programmed cell death (apoptosis), and can invade and spread (metastasize) to other parts of the body.

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While normal cells divide in a controlled, regulated manner and stop dividing once they contact neighbouring cells (contact inhibition), cancerous cells lose this regulation entirely, proliferate indefinitely, evade programmed cell death, and gain the ability to invade surrounding tissue and spread to distant body parts.

Cancerous cell vs. normal cell — key differences

1. Rate and control of cell division: Normal cells divide in a highly regulated, controlled manner in response to specific growth signals, and stop dividing once tissue repair/growth needs are met. Cancerous cells, due to mutations in genes controlling the cell cycle (oncogenes/tumour suppressor genes like p53), divide in an uncontrolled and unregulated manner, proliferating continuously regardless of the body's needs.
2. Contact inhibition: Normal cells display contact inhibition — they stop dividing once they come into contact with neighbouring cells, forming an organized monolayer. Cancer cells lose contact inhibition, so they continue to divide and pile up over one another, forming a mass called a tumour.
3. Differentiation: Normal cells generally differentiate into specialized cell types with specific functions. Cancer cells largely fail to differentiate and remain in a more primitive, undifferentiated proliferative state.
4. Apoptosis (programmed cell death): Normal cells that are damaged or no longer needed undergo a regulated, "clean" self-destruction process called apoptosis. Cancer cells evade/escape apoptosis, allowing damaged, potentially harmful cells to survive and keep dividing. …