Thursday, 15 May 2014

"20 scientific facts seldom taught to students" critically reviewed #13

It should be evident by now that John Collyer's '20 scientific facts seldom taught to students' serve only to emphasise the intellectual bankruptcy of his attacks on evolution. His thirteenth 'fact' is memorable for its utter mangling of molecular biology:
"The DNA helix in each cell requires twenty different proteins for its structure. These specific proteins can only be produced under the direction of the information in the DNA; therefore the whole complex system must have been formed complete from the beginning of life." 
DNA is not a protein, but a polymer made from four different nucleotides, adenine, guanine, cytosine, and thymine. Proteins are polymers of amino acids - the 20 standard amino acids are encoded by the genetic code which is encoded in DNA and messenger RNA sequences. It is painfully clear that Collyer has confused these two concepts.
Even if we overlook this blunder, Collyer is once more conflating abiogenesis with evolution, and trading on the argument from personal incredulity. Once again: abiogenesis remains one of the great unsolved problems in biology. However, the inability of laypeople with zero experience or background in biochemistry, genetics, and molecular biology - disciplines directly related to abiogenesis - to construct a plausible model for the evolution of the genetic code means nothing.

Chemical structure of DNA. (Source: Wikipedia)

Primary protein structure - amino acid chain (Source: Wikipedia)

The DNA sequence of a gene encodes the amino acid sequence of a protein. (Source: Wikipedia)

As I have previously touched on abiogenesis, I will not waste further time other than to point out that the origin of the DNA replication system is an area of intense research, and there are many solid hypotheses about how the DNA system could have evolved. There is strong evidence for an evolutionary origin of this system. For example, it is quite likely that transfer RNA is older [1] than its cognate aminoacyl-tRNAsynthetase. This is enough to show that the whole complex system did not form complete.


1. de Pouplana LR et alGenetic code origins: tRNAs older than their synthetases?Proc. Natl. Acad. Sci. USA (1998) 95:11295-11300