Final answer:
Defective proteins involved in apoptosis can result in uncontrolled cell growth, leading to cancer, autoimmune diseases due to the failure to eliminate malfunctioning immune cells, and developmental abnormalities arising from the improper removal of cells during organismal development.
Step-by-step explanation:
Defects in proteins that regulate apoptosis can have significant impacts on an organism. For example, the p53 protein is crucial in controlling cell division and initiating apoptosis when DNA is damaged. A defect in p53 can prevent it from signaling for DNA repair or triggering apoptosis, allowing cells with damaged DNA to proliferate. This may lead to the development of tumors, as mutated p53 genes are found in over 50 percent of human tumor cells.
Furthermore, apoptosis is essential in processes such as T-cell development, where it eliminates T-cells that incorrectly bind to self proteins, preventing autoimmune diseases. In developmental processes, apoptosis is critical for shaping structures by removing unneeded cells, as seen in the separation of fingers and toes during vertebrate development. If apoptosis does not occur due to protein malfunctions, it can result in developmental abnormalities.
Overall, the tight regulation of apoptosis is vital, and when proteins involved in this process are defective, it can lead to uncontrolled cell growth, impaired immune responses, and developmental issues.