Thursday, May 22, 2008

FF 7, Dicer

The embryo of the fruit fly has DNA which detects proteins that are diffusing toward it. These proteins can attach to the DNA to turn on, or promote the genes to produce their own proteins which will become part of the adult fly. Therefore, the genes can be in the 'on' or 'off' state. John Lennox in his book God's Undertaker (mentioned in the last post) puts the difference between a gene being on and off in mathematical terms. For every gene that has receptors for either producing or not producing, this is a "switch" at any given time. Just the on and off, without considering grades of difference as there are in the embryo, puts each of those genes to the base 2 and the number of switches as its exponent. Considering there are around 13,000 genes in the fruit fly, this gets to be a big number. The number 2^13,000 can be converted to base 10 to about 10^3900 (see Exponent link on right for explanation of exponents, ^) which gives you the number of different states the total set of genes could be in at any one time.

So, when you think about how a fruit fly could have evolved from a single cell, you have to think about how all these genes with hundreds of base pairs each could get to produce proteins which in turn could turn the genes back on at just the right time to produce not only a living cell that it came from but other manifestations that would give heads and lungs and blood cells and vessels and muscles and the multitude of systems we need.

That brings us to Dicer (pictured here). Dicer is found in humans, fruit flies, and single-celled animals. Proteins are often used to help reactions of other molecules in the cell. These are called enzymes.

Dicer does an amazing thing. RNA, as we've seen, is copied from the DNA of cells in the process of protein production. Dicer is required for a metabolic pathway that cuts up RNA so it can repress or turn off gene expression (in other words, stops the gene from producing the RNA that will help produce a particular protein). Genes sometimes need to produce proteins and sometimes need to not produce them because there are already enough in the body. This is a feedback mechanism.

Now, in the fruit fly embryo which we've just discussed, we had proteins which turned on gene expression. The DNA had sets of genes which detected molecules of protein that diffused to the embryo's DNA. When the gene and the protein combined (because they were a chemical "fit"), the gene started making proteins for the particular part of the body that the fruit fly would develop (head, thorax, tail).

This regulation is another level of complexity. You not only have the genes with their specific order, but then they work in concert with other genes to get the right things done in the body. Considering there are thousands of genes and up to a million different types of protein products (humans), that's a super-switching apparatus.
Remember, William Dembski put the maximum number of events in the entire universe, even if it started 14 billion years ago, at 10^150. This number comes from the estimated number of particles in the universe (10^80) times the maximum number of reactions per second (10^45) times the number of seconds in the universe (10^25--which even includes future time). At base 2, your bound for the entire number of events is about 2^500. To be fair, there could be other proteins which do the same job and could be substituted for the ones used. But there have been experiments that show that only one protein in 10^77 is usable (see Stephen Meyer book, Signature in the Cell). That is because the amino acids have to line up right to get the right shape for the protein to work. As you see in Dicer, it has a very unique shape and that is because cross-bridges and other types of chemical bonds in the amino acids can hold it in the shape it has. Once you reach 2^500, you have used up all events of the universe to try to get it right.

Eventually, John Lennox stopped counting because the probabilities for these organisms to happen by chance became too great. Though there will probably be endless efforts by some to prove materialistic, naturalistic evolution is right, it is proper when one beholds these wonders to say, "Praise the Lord!"

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