Question 9

HeLa cells are considered immortal because they multiplied every 24 hours in culture and never stopped.

HeLa cells are defined as immortal due to their unique ability to continuously divide and multiply indefinitely in laboratory conditions. This characteristic was first observed by George Gey when he discovered that Henrietta Lacks's cells doubled in culture every 24 hours without cessation.

A) they didn't die even when exposed to toxins.

This option is incorrect as it implies a resistance to toxins, which is not the primary reason HeLa cells are termed immortal. While HeLa cells may exhibit resilience in certain environments, their immortality is specifically attributed to their continuous cell division rather than their survival against toxic substances.

B) they multiplied every 24 hours in culture and never stopped.

This statement accurately describes the defining feature of HeLa cells. Their ability to replicate continuously in culture, doubling approximately every 24 hours, is what classifies them as immortal, allowing them to serve as a crucial resource for various medical research advancements.

C) they can cure diseases when injected into patients.

This option is misleading. HeLa cells themselves do not cure diseases; rather, they are used in research to understand disease mechanisms and develop treatments. The immortal nature of HeLa cells allows researchers to study these diseases more effectively, but it does not imply that the cells have therapeutic properties when injected into patients.

D) they led to a cure for HIV and cancer.

While HeLa cells have played a significant role in research that contributed to advancements in treatments for diseases like HIV and cancer, this statement overstates their role. HeLa cells are tools for research rather than direct cures, and their immortality is not based on leading to cures but rather on their continuous growth in culture.

Conclusion

In summary, option B is the only one that correctly identifies the reason HeLa cells are considered immortal, emphasizing their unique capacity for continuous division. Other options either misrepresent the nature of HeLa cells or inaccurately attribute direct therapeutic capabilities to them. Hence, understanding HeLa cells' role in scientific research relies on their remarkable ability to proliferate indefinitely in culture.