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FP — I am not a biologist, and neither are most of my readers… How do you explain that we should understand the cell as a network?
FC — Let me contrast a living cell and a machine, say a clock or a car. When you build the machine, you manufacture the parts; you do some machining and engineering to manufacture them as precisely as you can. Then you fit them together according to a preexisting design. And then the machine works and you can mass produce it.
A living cell works quite differently. It's a network of processes that actually continuously build the parts. The parts from the cell do not come from a factory outside the cell; they are created by the cell itself. And when I say parts, I mean all the macromolecules and cellular structures.
Small molecules come in through the cell membrane — the food, the oxygen, the carbon and so on. The food comes in and is broken down. But each macromolecule, for example each enzyme, which is a protein with a very complex structure, is synthesized by the cell itself. The process of protein synthesis is now quite well known. It's a complex process which involves the genetic information in the DNA, in the genome. The DNA strands unwind a little bit, and then the part that is needed for the protein is copied onto a macromolecule called RNA. Then the RNA takes that information to a place where the protein is built. It's called a ribosome and at the ribosome, the protein is synthesized from elements called amino acids. They are put together in a certain order, and that order is given by the genetic code.
This is the basic way of constructing a protein. That process needs the basic elements, the amino acids, which float around in the chemical soup around the ribosome. It also needs energy to capture the amino acids and put them into place. In biochemistry, these processes can only happen if there are catalysts. They are facilitators of the process and are not affected by the process. They are part of the reaction but come out of the reaction unchanged, and can go on to catalyze another reaction.
The energy comes in the form of special molecules called ATP. They are special kinds of phosphates that change their structure in various steps, and in each step they release energy. They are energy carriers.
The catalysts are the enzymes. A dozen different enzymes are needed for that protein to be built. Where do they come from? Everything has to come from the cell. The ATP molecules are built in the mitochondria. They are the power houses of the cell. They form the energy carriers to supply the entire cell with energy. The enzymes are built in the same way as proteins are built, because they themselves are proteins. Each of the enzymes that helps in the synthesis of a protein has itself been synthesized somewhere else in the same type of process. If you put all that together you have a network, and a very complex network, because each molecular structure, each molecular unit, has been produced by other molecular processes, has been catalyzed by other molecular units. In this way, the entire network continually produces itself. You can draw a diagram of the various cellular structures, and you will see that when the energy carriers are created in the cell's powerhouses, they swarm out over the entire cell and go to all the processes where energy is needed. The same thing happens when enzyme are created. They too swarm out, and the amazing thing is that these processes happen very fast. Synthesis of very complex molecules goes on all the time and goes on very fast. The macromolecules constantly travel to different areas where they are engaged in chemical processes. So these material structures that form the links between two processes are the links in the network. The network is a nonmaterial network; it's a functional network where these structures interconnect biochemical processes.
FP — When you use the word "network," sometimes you give the impression that it is a pattern, some times you give the impression that it is a process. There are structures in there. That is a useful word that you do not have to explain each time. It begins to be a paradigm in the sense in which Kuhn uses the term.
FC — Very true. Let me be precise about the cellular network. There are three elements in there. There are processes, which are processes of production. There are structures, the things that are produced. And these molecular structures, once they are produced, go on to contribute to other production processes. They are the links in a network of production processes, which is a specific pattern. So, you have processes, structures, and patterns.
And you are right, I don't need to define network. When you go into more details and deal with different kinds of networks you need to define these specific networks. But everybody knows what a network is.
FP — Kuhn says that you use it because you don't define it. That's why it is useful and becomes a paradigm. Let's move to another issue, autopoiesis. What is it?
FC — It is exactly what I just explained to you. That is autopoiesis. Over the years, I came to use less and less technical terms. I use "autopoiesis” in my book, but I give many lectures where I don't use it at all. What "autopoiesis" means is self-generation. Living networks are self-generating. The unifying pattern of life is a self-generating network, an autopoietic network.