Question

The property of cellular immortality refers to a cell's ability to A. grow new blood vessels. B. invade through the basement membrane of its tissue. C. resist apoptosis. D. continue to divide without limit to the number of cell generations. E. grow tumors at multiple sites.

Short answer

Answer: The correct property of cellular immortality is the ability to continue to divide without limit to the number of cell generations.

Step-by-step solution

Understanding cellular immortality

Cellular immortality refers to the ability of a cell to divide and reproduce indefinitely without undergoing the normal process of cellular aging or cell death. This property is common in certain types of cells, such as cancer cells, which can continue to divide and grow uncontrollably.

Analyzing the given options

Go through each option and compare it with the definition of cellular immortality: A. The ability to grow new blood vessels is related to angiogenesis, which is a different property. B. Invading through the basement membrane of its tissue is related to the metastatic properties of cells, rather than cellular immortality. C. Resisting apoptosis refers to the ability of a cell to avoid programmed cell death, which is a crucial factor in cellular immortality but not the complete definition of it. D. Continuing to divide without the limit to the number of cell generations is the exact definition of cellular immortality, as it means the cell can replicate indefinitely. E. The ability to grow tumors at multiple sites is a characteristic of metastatic cancer cells, not specifically relating to cellular immortality.

Identifying the correct answer

Comparing the options with the definition of cellular immortality, it is clear that option D - "continue to divide without limit to the number of cell generations" is the correct answer. This is because it directly describes the property of a cell being able to divide indefinitely without undergoing cellular aging or cell death.

Key concepts

Cell Division

The process of cell division is fundamental to all living organisms as it allows for growth, development, and tissue repair. In its simplest form, cell division is the process by which a parent cell divides into two or more daughter cells. This usually occurs via the cell cycle, which includes phases such as mitosis or meiosis. However, not all cells have the same capacity to divide endlessly. Most somatic (body) cells have a predefined number of divisions, known as the Hayflick limit. After reaching this limit, cells typically enter a state of senescence and eventually die.

Contrastingly, some cells, like stem cells and cancer cells, exhibit properties that allow them to divide indefinitely, a phenomenon known as cellular immortality. These cells bypass the normal regulatory checkpoints that trigger cell death or senescence, allowing for continuous replication. Understanding the regulation of cell division is crucial in fields such as cancer research, where the goal is to find ways to control or halt the unregulated division of cells.

Apoptosis Resistance

Apoptosis is a form of programmed cell death that is an essential component of cell turnover and development. It also serves as a protective mechanism to eliminate damaged or potentially harmful cells. A hallmark of cancer cells is their acquired resistance to apoptosis, allowing them to evade this natural safeguard. Resistance to apoptosis can occur due to mutations in genes that regulate the cell cycle, the presence of survival signals, or the loss of death signals.

• Mutations can alter normal cell functions, enabling cells to ignore apoptotic signals and continue to survive and proliferate.
• Survival signals often come from growth factors that bind to cell receptors and activate pathways that promote cell survival and division.
• Loss of death signals involves the inactivation of pathways that normally initiate apoptosis in response to cellular stress or damage.

Understanding how cells resist apoptosis is key to developing therapies that can reinstate the apoptotic process, particularly in the treatment of cancer, where reactivation of cell death pathways could prevent the growth and spread of tumors.

Cancer Cells

Cancer cells are distinguished from normal cells by several key characteristics, including their ability to grow and divide without control and evade mechanisms that would typically regulate or terminate their life span. These cells undergo a series of mutations that confer a variety of survival advantages. These advantages include unrestricted cell division, apoptosis resistance, sustained vascularization to support growth (angiogenesis), and the capacity to spread to other parts of the body (metastasis).

One critical aspect that students often misunderstand is the distinction between normal cell replication necessary for bodily functions and the anarchic proliferation of cancer cells. Cancer cells manipulate various molecular pathways to secure their immortality. For instance, they often reactivate the enzyme telomerase, which prevents the shortening of telomeres—the protective ends of chromosomes that typically erode during cell division, acting as a biological clock triggering senescence.

Another concept vital to grasp is the tumor microenvironment, which cancer cells modify to support their growth and protect themselves from the immune system. This complex interaction involves various cell types and signaling molecules that create a supportive niche for cancer survival and proliferation. Understanding these intricacies helps in the development of targeted treatments like immunotherapies, which aim to disrupt cancer cells' evasion tactics.