Originality of Proteins: complex - non transitional forms

Originality in evolution

We have already seen that the strong similarities in the structure of the cell stands out, and this happens among the most diverse forms of life. It is huge homological. The next problem is the unexpected side of it. To understand this we must first know a little more about biochemistry.

All of life is made up of tiny cells. In our body there are thousands of billions of cells. The operation of the cell is due substantially to ingenious molecules which we call proteins. These are large molecules consisting of thousands of atoms. And the special feature of these molecules is their incredible complexity. It only became clear during the last 25 years how proteins are actually extremely unlikely.

While man has not yet been able to design a single protein, the human body appears to exist from 30,000 different proteins, all equipped for a very specific task.

These proteins are long chains of amino acids. These amino acids are best pictured as beads you can string together to form a protein. There are 20 possible amino acids and one protein has hundreds lined up in a very specific order. Depending on the order, this chain can adopt a stable folded 3D shape and fulfill a specific chemical or mechanical function. If you compose arbitrary amino acids to a 'candidate' protein is the approximately one in a billion probability that the protein adopts such a stable conformation and hence can work. But the chances that such a stable protein also has a useful function, is obviously much smaller. Proteins are thus extremely unlikely! So the question is: how do these proteins occur?

Evolutionary biologists are always thought that these proteins are evolutionary emergence. And as one can reconstruct the supposed evolution from the similarities in the fossils, reconstructing the supposed evolution from the similarities of proteins. What is the problem? Precisely the huge similarities!

Because of the enormous homology, it is found among the proteins that there are much less transitional forms than in the fossil record. Some of the proteins which are found in a wide variety of organisms, are 80% identical. It appears that one can reconstruct only for 20% of evolution, the rest is, after all, the same. The obvious conclusion is that the evolution of these proteins in the more distant past took place but then again there are two notable findings. The first is that some proteins only occur in later organisms so that it is expected that they should have emerged more recently. Secondly, that the 20% that is different, on closer inspection is apparently the least important part of the protein. Proteins will seem quite original.