Nature Reviews Molecular Cell Biology states, “Today biology is revealing the importance of ‘molecular machines’ and of other highly organized molecular structures that carry out the complex physico-chemical processes on which life is based.” Likewise, a paper in Nature Methods observed that “most cellular functions are executed by protein complexes, acting like molecular machines.” The molecular machines that we find are exceedingly complex and perform many of the functions our body requires even if we don’t have any awareness of them.
In 1996, Michael Behe published a book Darwin’s Black Box. Dr. Behe is a biochemist at Leheigh University. His thesis is that these micro-machines are not only complex but also demonstrate a property of irreducible complexity. Irreducibly complex means a single system which is composed of several interacting parts that contribute to the basic function, and where the removal of any one of the parts causes the system to effectively cease functioning. For example the mousetrap is a simple machine that will not work unless all the parts are in place. If the latch were only half in length, the whole machine will not work. Using the mousetrap example, there is no pathway for the mousetrap to be developed is a gradual, step-wise path. Behe argues that the same it true for the micro-machines that we find in biological systems. It is not just that they are complex but also that all the parts have to work completely for the machine to work at all. There is no logical theory of how these machines could have developed through a process of evolution. In fact, Behe shows that they cannot. Darwin himself made the following statement: “If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.” At that time, Darwin was not aware of the complex micro-machines that are in the body. Now as Behe has shown, these could not have been developed in a step-wise manner. Of course Behe's idea is rejected by many biologists since there is an implication to this theory. There is also a refusal to even talk about the available evidence. I’ll talk more about that reaction in a later blog. For now, here are some irreducibly complex systems. There are many more.
1. Bacterial Flagellum: The flagellum is a rotary motor in bacteria that drives a propeller to spin, much like an outboard motor, powered by ion flow to drive rotary motion. Capable of spinning up to 100,000 rpm, one paper in Trends in Microbiology called the flagellum “an exquisitely engineered chemi-osmotic nanomachine; nature’s most powerful rotary motor, harnessing a transmembrane ion-motive force to drive a filamentous propeller.” Due to its motor-like structure and internal parts, one molecular biologist wrote in the journal Cell, “more so than other motors, the flagellum resembles a machine designed by a human.” Genetic knockout experiments have shown that the E. coli flagellum is irreducibly complex with respect to its approximately 35 genes. Despite the fact that this is one of the best studied molecular machines, a 2006 review article in Nature Reviews Microbiology admitted that “the flagellar research community has scarcely begun to consider how these systems have evolved.”
2. Eukaryotic Cilium: The cilium is a hair-like, or whip-like structure that is built upon a system of microtubules, typically with nine outer microtubule pairs and two inner microtubules. The microtubules are connected with nexin arms and a paddling-like motion is instigated with dynein motors. These machines perform many functions in Eukaryotes, such as allowing sperm to swim or removing foreign particles from the throat. Michael Behe observes that the “paddling” function of the cilium will fail if it is missing any microtubules, connecting arms, or lacks sufficient dynein motors, making it irreducibly complex.
3. Aminoacyl-tRNA Synthetases (aaRS): aaRS enzymes are responsible for charging tRNAs with the proper amino acid so they can accurately participate in the process of translation. In this function, aaRSs are an “aminoacylation machine.” Most cells require twenty different aaRS enzymes, one for each amino acid, without which the transcription/translation machinery could not function properly. As one article in Cell Biology International stated: “The nucleotide sequence is also meaningless without a conceptual translative scheme and physical ‘hardware’ capabilities. Ribosomes, tRNAs, aminoacyl tRNA synthetases, and amino acids are all hardware components of the Shannon message ‘receiver’. But the instructions for this machinery is itself coded in DNA and executed by protein ‘workers’ produced by that machinery. Without the machinery and protein workers, the message cannot be received and understood. And without genetic instruction, the machinery cannot be assembled.” Arguably, these components form an irreducibly complex system.
4. Blood clotting cascade: The blood coagulation system “is a typical example of a molecular machine, where the assembly of substrates, enzymes, protein cofactors and calcium ions on a phospholipid surface markedly accelerates the rate of coagulation.” According to a paper in BioEssays, “the molecules interact with cell surface (molecules) and other proteins to assemble reaction complexes that can act as a molecular machine.” Michael Behe argues, based upon experimental data, that the blood clotting cascade has an irreducible core with respect to its components after its initiation pathways converge.
In 1996, Michael Behe published a book Darwin’s Black Box. Dr. Behe is a biochemist at Leheigh University. His thesis is that these micro-machines are not only complex but also demonstrate a property of irreducible complexity. Irreducibly complex means a single system which is composed of several interacting parts that contribute to the basic function, and where the removal of any one of the parts causes the system to effectively cease functioning. For example the mousetrap is a simple machine that will not work unless all the parts are in place. If the latch were only half in length, the whole machine will not work. Using the mousetrap example, there is no pathway for the mousetrap to be developed is a gradual, step-wise path. Behe argues that the same it true for the micro-machines that we find in biological systems. It is not just that they are complex but also that all the parts have to work completely for the machine to work at all. There is no logical theory of how these machines could have developed through a process of evolution. In fact, Behe shows that they cannot. Darwin himself made the following statement: “If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.” At that time, Darwin was not aware of the complex micro-machines that are in the body. Now as Behe has shown, these could not have been developed in a step-wise manner. Of course Behe's idea is rejected by many biologists since there is an implication to this theory. There is also a refusal to even talk about the available evidence. I’ll talk more about that reaction in a later blog. For now, here are some irreducibly complex systems. There are many more.
1. Bacterial Flagellum: The flagellum is a rotary motor in bacteria that drives a propeller to spin, much like an outboard motor, powered by ion flow to drive rotary motion. Capable of spinning up to 100,000 rpm, one paper in Trends in Microbiology called the flagellum “an exquisitely engineered chemi-osmotic nanomachine; nature’s most powerful rotary motor, harnessing a transmembrane ion-motive force to drive a filamentous propeller.” Due to its motor-like structure and internal parts, one molecular biologist wrote in the journal Cell, “more so than other motors, the flagellum resembles a machine designed by a human.” Genetic knockout experiments have shown that the E. coli flagellum is irreducibly complex with respect to its approximately 35 genes. Despite the fact that this is one of the best studied molecular machines, a 2006 review article in Nature Reviews Microbiology admitted that “the flagellar research community has scarcely begun to consider how these systems have evolved.”
2. Eukaryotic Cilium: The cilium is a hair-like, or whip-like structure that is built upon a system of microtubules, typically with nine outer microtubule pairs and two inner microtubules. The microtubules are connected with nexin arms and a paddling-like motion is instigated with dynein motors. These machines perform many functions in Eukaryotes, such as allowing sperm to swim or removing foreign particles from the throat. Michael Behe observes that the “paddling” function of the cilium will fail if it is missing any microtubules, connecting arms, or lacks sufficient dynein motors, making it irreducibly complex.
3. Aminoacyl-tRNA Synthetases (aaRS): aaRS enzymes are responsible for charging tRNAs with the proper amino acid so they can accurately participate in the process of translation. In this function, aaRSs are an “aminoacylation machine.” Most cells require twenty different aaRS enzymes, one for each amino acid, without which the transcription/translation machinery could not function properly. As one article in Cell Biology International stated: “The nucleotide sequence is also meaningless without a conceptual translative scheme and physical ‘hardware’ capabilities. Ribosomes, tRNAs, aminoacyl tRNA synthetases, and amino acids are all hardware components of the Shannon message ‘receiver’. But the instructions for this machinery is itself coded in DNA and executed by protein ‘workers’ produced by that machinery. Without the machinery and protein workers, the message cannot be received and understood. And without genetic instruction, the machinery cannot be assembled.” Arguably, these components form an irreducibly complex system.
4. Blood clotting cascade: The blood coagulation system “is a typical example of a molecular machine, where the assembly of substrates, enzymes, protein cofactors and calcium ions on a phospholipid surface markedly accelerates the rate of coagulation.” According to a paper in BioEssays, “the molecules interact with cell surface (molecules) and other proteins to assemble reaction complexes that can act as a molecular machine.” Michael Behe argues, based upon experimental data, that the blood clotting cascade has an irreducible core with respect to its components after its initiation pathways converge.
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