As I have mentioned in class, I think that bacteria and viruses appear to possess features consistent with the idea that they are designed to deliver agents to cells. For instance, their size is conducive to cell interaction and many possess elaborate motors , docking and delivery systems. In fact, the bacterial flagellum which is often advertised as having one function, actually demonstrates many functions, i.e. it is a docking/binding agent as well as a motor, it also appears to be a receptor in some instances. Thus the flagellum demonstrates co-option; it has more than one function, an idea that many intelligent design theorists don’t like. In addition some bacteria can control the actin polymerization inside cells inducing the cells to make “cellular arms” or pseudopods. Thus they induce the cell pseudopods to engulf them and they enter the cell in this manner. Recently, researchers have used bacteria to deliver a virus to a cell which induced profound genetic changes in the cell. Viruses themselves possess several elaborate mechanisms for engaging cells and entering cells. Viruses not only deliver genetic information to cells, but they can deliver proteins, they can control intracellular biochemistry and they can deliver membranes and membrane proteins. Take for instance the flu virus. It is an enveloped virus. Technically when it leaves a cell it takes along some membrane from that cell. Could it be that everytime you get a flu, you also get some proteins and membrane components from your friends? What are the long term and short term implications of this? But then again, viruses and bacteria can cause lots of problems. If these creatures were designed as extracellular delivery organelles, is this the best design?.... because it appears that with a few "slight modifications" they can become agents of cellular destruction.
1 Discuss the microbial extracellular organelle theory as described above. What are its strengths and weaknesses as a theory?
2 If bacteria and viruses are designed delivery agents, why does our immune system try to eliminate them? Or does it?