Answer:
Most cells removed from animals are not immortal because they have a limited capacity to divide. This is due to the shortening of telomeres, which are the protective caps on the ends of chromosomes.
Step-by-step explanation:
Each time a cell divides, its telomeres become shorter. Eventually, the telomeres become too short to protect the chromosomes, and the cell enters a state of senescence or dies. This process is known as the Hayflick limit, named after the scientist who discovered it.
However, some cells are able to bypass the Hayflick limit and become immortal. These include cancer cells and certain types of stem cells. Cancer cells can bypass the limit by activating telomerase, an enzyme that can rebuild telomeres. Stem cells can bypass the limit by using alternative mechanisms to maintain their telomeres, or by dividing more slowly than other cells.