Phospholipids are amazing molecules. Place them in a watery environment and they self associate into a spherical ball and make membranes. Membranes made of phospholipids are fluid structures which are sticky to themselves, so that they make a barrier which typically defines, in part, the outer boundry of a cell and helps hold things in the cell, yet it remains a fluid. Life would not work without these fluid barriers. Who would of thought of that? What a perfect idea for a membrane, a fluid barrier! We would be very stiff creations indeed if our membranes were not made out of these soapy molecules.
So we see in membranes the same principle we discussed regarding the idea that all macro-organisms are made of smaller pieces or entities we call cells, i.e., membranes are made of lots of smaller parts (phospholipids). Relatedly, we also see modularity, i.e., the parts are somewhat interchangeable and pliable. And this modularity and pliability allows for a lot of things to be stuck in membranes.
But, if phospholipids are sticky (self associate because of hydrophobicity) why don't all cells near one another, stick together and form one big clump....for instance when we bump into each other why don't we form one big glumpy smear of phospholipid humanity on the earth. How do pond organisms swim around with these sticky membranes and not get stuck or fuse together? In fact this is how some viruses work, they invade cells by fusing their outer lipid membrane envelope with the cell membrane, and they take advantage of this sticky/hydrophobic effect. Works like a charm. The virus fuses to the membrane and releases its contents ( at least some viruses work this way, not all do).
So my questions for this blog are;
1 Why and how do phospholipids self associate?
2 What prevents membranes from fusing with all other nearby membranes?
3 Could the self assembly of phospholipids be a posssible explanation for how the first cell membranes evolved?
4 When phospholipids form membranes in a water based environment, do they make membranes similar to the cell membranes we find in cells today?