We have discussed the lipids and proteins which make up the membranes in cells in lecture. Internal cell organelles are also composed of phospholipids and specialized membranes. One of the most bizarre membrane proteins is called the mitochondrial permeability transition pore (mPTP). This is a cluster of proteins which connect the inner mitochondrial membrane with the outer mitochondrial membrane and forms a pore. The pore only forms briefly under extreme cell stress conditions and essentially really messes up the mitochondria so that it reverses its function, and begins consuming ATP which usually kills the cell. In many cases this activity leads to apoptosis also called programmed cell death. This drastic measure often occurs after local cellular stress or stress of internal organs like during a heart attack. Just like Jason Bourne in the Bourne Identity, the identity of the mitochondria is difficult to determine, it is a unique mystery organelle in many ways, and like Bourne, it commits violence when stressed out....or is it that it commits violence to protect itself? Just what could the mitochondria be protecting?
This also raises a question about eukaryotic cell evolution. Mitochondria look like they come from bacteria. And thus it looks like eukaryotes evolved from prokaryotes. It is based on the idea that an ancient prokaryote engulfed another ancient prokaryote and this was the beginning of the evolution on internal organelles.
Perhaps though we are looking at this all wrong, perhaps mitochondria are the intracellular counterparts to extracellular bacteria. We know that many extracellular bacteria perform life supporting functions for higher level organisms. So why not consider mitochondria to be specialized intracellular bacteria which also supply life supporting functions for cells. It would be a design feature consistent with the idea of a master designer of all of life. Could the mitochondria have originally risen from an extracellular source? Or is it too vital to the function of plant and animal cells such that it is more likely that it was inserted upon the first creation of these organisms? Are both theories viable or does the data at hand support one theory over the other?
DUE APRIL 1
1 What are the different ways that a cell can die?
2 What is apoptosis? What are its benefits?
3 What would be the advantage to having the vital energy producing organelle also double as a death organelle?
4 Considering the idea that the mitochondria is a specialized internal bacterium, are there parallels in function between mitochondria and extracellular free living bacteria with respect to energy production and promotion of cell death?
5 Is the endosymbiosis theory logical with respect to the evolution of mitochondria?
6 Could God have created cells in this manner, by using an endosymbiotic process?
7 What are the supports in favor of endosymbiosis theory and the arguments against it. What do you believe based on the evidence?
8 Could God have created internal bacteria to do things inside our cells, similar to the idea that bacteria do important things for creatures when they are outside of cells?
