Researchers have extended the life of a human cell by: a. removing the caps of DNA molecules. b. injecting it with telomerase. c. rearranging the DNA sequences. d. splicing the 18th and 19th chromosome.
The correct answer and explanation is:
The correct answer is b. injecting it with telomerase.
Explanation:
Human cells, like all eukaryotic cells, contain chromosomes made up of DNA. The ends of chromosomes have protective caps called telomeres, which prevent the chromosomes from deteriorating or fusing with other chromosomes. However, each time a cell divides, the telomeres shorten slightly, and when they become too short, the cell can no longer divide. This is one of the key factors in cellular aging and death.
Telomerase is an enzyme that adds repetitive sequences to the ends of telomeres, effectively lengthening them. In some cells, such as germ cells, stem cells, and certain cancer cells, telomerase is active and can keep telomeres from shortening during cell division. In most somatic (non-reproductive) cells, however, telomerase activity is low or absent, leading to telomere shortening and eventual cell death.
Researchers have been exploring the potential of telomerase as a tool for extending the lifespan of human cells. By injecting cells with telomerase or introducing genes that code for telomerase, they can prevent the telomeres from shortening, allowing the cell to divide more times before reaching its limit. This method has been shown to extend the life of cells in laboratory conditions, offering insights into how aging might be slowed or even reversed at the cellular level.
However, while this approach shows promise for extending cellular lifespan, it also has significant risks. Telomerase activation in somatic cells could potentially lead to uncontrolled cell division, which is a hallmark of cancer. As a result, there is a careful balance that must be struck between promoting healthy cell longevity and avoiding the risk of promoting tumor growth.
In contrast to other options:
- a. removing the caps of DNA molecules would expose the chromosomes to damage and is not a strategy for extending cell life.
- c. rearranging the DNA sequences could disrupt normal cellular function and does not directly affect telomere length.
- d. splicing the 18th and 19th chromosome is an incorrect or irrelevant method, as these chromosomes are not involved in telomere lengthening.
Thus, injecting telomerase is the most relevant and effective approach for extending cell lifespan.