Question

There are more than 100 types of cancer caused by mutation of cellular genes. Normal cells are limited to about 50 to 60 divisions before they die. Cancer cells do not have a division ____ and are considered to be immortal, that is, they keep on dividing, unless they are killed or their host dies.

A) Cycle
B) Barrier
C) Limit
D) Clock

Answer 1

Cancer cells bypass the normal division limit known as a division 'limit', which allows them to divide indefinitely, become immortal, and potentially form tumors by not responding to normal cell division regulation signals. The correct option is c.

Step-by-step explanation:

The division limit that cancer cells do not have is known as a division limit. Normal cells are generally confined to around 50 to 60 divisions, at which point they go through a process called senescence and stop dividing.

This process is controlled by DNA sequences called telomeres at the ends of chromosomes, which shorten each time a cell divides. In contrast, cancer cells often activate an enzyme called telomerase, which rebuilds these telomeres, allowing the cells to divide indefinitely and become essentially immortal.

This is a key characteristic of cancer cells and is pivotal to their ability to grow and spread through the body, forming tumors and potentially spreading to other areas in a process known as metastasis.

The uncontrolled growth results because the cells do not heed the normal signals to stop dividing or to die, a process known as programmed cell death or apoptosis. The correct option is c.