Question

Apoptosis: Apoptosis is utilized by human cells to terminate cell growth for and resorb appendages like vestigial tails in human development. 3) How does the body know where to resorb these structures and how far back to apoptize the cells that make them up? 4) How does the body know when to turn this apoptotic signaling on during development so these events don't happen too soon or too late?

Answer 1

3.Apoptosis is mediated by proteolytic enzymes called caspases, which trigger cell death by cleaving specific proteins in the cytoplasm and nucleus. Caspases exist in all cells as inactive precursors, or procaspases, which are usually activated by cleavage by other caspases, producing a proteolytic caspase cascade. Apoptosis caused by CDV is typically induced via the extrinsic pathway, which activates caspases that disrupt cellular function and eventually leads to the cells death. In normal cells, CDV activates caspase-8 first, which works as the initiator protein followed by the executioner protein caspase-3.

4. "One highly unusual form of cell death occurs in cells infected by certain plasmid viruses that instruct the host cell to create two chemicals: a long-lived toxin and an unstable antidote. During replication, about 1 percent of the cells lose the parasitic plasmid in their DNA; the daughter cells still contain the toxin but can no longer manufacture the antidote, so they die. This is a rare instance of cellular murder rather than suicide. Apoptosis also plays a key role in human development.This process occurs in all sorts of vertebrate species that have finger- or toe-like digits, and less apoptosis results in more webbing between the digits. Sometimes, if a small mistake happens during finger or toe development, apoptosis may be incomplete (leading, for instance, to fused toes).