Difference between revisions of "Blood clotting cascade"
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Revision as of 21:16, July 10, 2007
A number of proteins are involved in the series of events that lead to vertebrate blood clotting.
Michael Behe describes it thus:
When an animal is cut, a protein called Hagemann factor (XII) sticks to the surface of cells near the wound. Bound Hagemann factor is then cleaved by a protein called HMK to yield activated Hagemann factor. Immediately the activated Hagemann factor converts another protein, called prekallikrein, to its active form, kallikrein. [1]
Behe, who is a supporter of Intelligent Design, argues that all of these components must be in place before the system will work:
...none of the cascade proteins are used for anything except controlling the formation of a clot. Yet in the absence of any of the components, blood does not clot, and the system fails. [2]
Although, as Behe points out, Factor XII initiates the "cascade of proteins" in vertebrates, dolphins lack Factor XII [3] and yet their blood is known to clot. This appears to contradict the notion of irreducible complexity in regard to this process.