Final answer:
The bcl2 gene expression in response to apoptosis-inducing signals can be disrupted in cancer cells due to mutations preventing signaling initiation, loss of apoptosis receptors, or overexpression of apoptosis inhibiting growth pathways. Cell death through apoptosis is crucial in T-cell development and vertebrate digit formation. Disruptions can lead to cancer via unchecked cell division or accumulation of faulty proteins.
Step-by-step explanation:
Understanding Apoptosis in Cancer Cells
The expression of the anti-apoptotic bcl2 gene is induced in response to various signals that a cell may encounter. In the case of a scientist observing that a cancer cell line fails to die when exposed to an inducer of apoptosis, there are multiple hypotheses that could explain this phenomenon. One possible explanation is that the cells have a mutation preventing the initiation of apoptosis signaling. Another possibility is that the cells have lost expression of the receptor for the apoptosis-inducing ligand. Additionally, the cells may overexpress a growth factor pathway that inhibits apoptosis.
Apoptosis, often referred to as programmed cell death, is essential in normal development and in the removal of damaged cells. For instance, during T-cell development in the immune system, apoptosis is triggered to eliminate cells that incorrectly target 'self' proteins, which could lead to autoimmune diseases. Furthermore, in vertebrate development, apoptosis is crucial to the elimination of unneeded cells, such as the web-like tissue between developing fingers and toes, allowing for proper digit formation.
Overall, when apoptosis is disrupted, it can lead to uncontrolled cell proliferation and potentially cancer. Key pathways involve the release of cytochrome C in response to pro-apoptotic signals and the action of the fas ligand on target cells. If any part of this chain of events is disrupted, faulty proteins may accumulate, or cells may continue dividing unchecked, both situations that can contribute to the progression of cancer.