Monkeying around with the genome: more differences between human and chimp DNA.

A recent surge of fascinating molecular studies between human and chimp DNA has established greater differences between the two species making evolutionary ancestry unlikely. Even the level of complexity discovered in just the human genome has demonstrated a level unimaginable a decade ago. A new piece of evidence supporting “glaring differences” between ape and human genetics, as the November 15, 2007 issue of Science Daily posted, includes how genetic information is handled after it is transcribed into RNA molecules. RNA molecules are information molecules intermediate between the gene composed of DNA and proteins that carry out the processes of life. RNAs of this type, and there are other types of RNA molecules, are considered “messengers” since they are copies or transcripts of instructions from the DNA. They are far more mobile in living cells than the DNA molecule. They take the instructions from the site of the gene into the cellular cytoplasm for use in building or “translating” the DNA’s code into functional protein molecules like muscle, enzymes, and hair.

A well-known fact about the genomes of multicellular organism is that the each gene is not limited to code for just a single protein. It is not a one to one relationship. For example, although the human genome gives rise to some 100,000 different proteins, these proteins are the result of around 21,000 genes. It was once thought that for every gene, only one protein could be made.  For some time now it has been known that one gene may give rise to multiple different proteins. How is this possible?

At this point it is necessary that some fundamental molecular biology be explained. So if this is old news to you, continue to follow the article down below. If this is new to you, let’s look at a genetic mechanism called “alternate splicing” which might help you understand how one gene can give rise to multiple proteins. After this we can return to the issue of how this feature of genetics adds greatly to our understanding of why an ape is an ape and a human is a human; it will also add to the real issue at stake, are humans a product of animal evolution and do genetic studies support such?

A gene is composed of many informational DNA sequences. Many of these sequences direct the manufacture of an informational molecule called RNA or mRNA for short. Some sequences in the DNA tell the cell to “transcribe” the DNA into a mRNA molecule. Some sequences say “start here”, other sequences say “stop at this point” and still others contain sequences that will eventually be cut out of the messenger molecule. This cutting of sequences along the messenger molecule allows for other regions of the molecule to be spliced together giving rise to coding regions alternate to that of the original gene. It is the “alternate splicing” that allows one gene to give rise to many different proteins through the intermediate messenger molecule, mRNA. Here are some illustrations that may help you understand how this is done.

Below is a typical gene found on a stand of DNA. It has many sequences which direct the biology of the cell to perform certain controlled events in order for the genetic activity to have any functional meaning or influence in the cell. Some switches turn on or promote gene transcription and others turn it off. Embedded in the transcript, the mRNA, are signals that tell the cell how to use the messenger; where to start decoding and when to stop decoding for the production of protein. The alignment of certain sequences from the 4 letter DNA alphabet A, T, G, C that create the code “ATG” is universal for Start. In most cells this code starts every protein sequence with the amino acid called methionine. The codes ”TAG” or “TAA” are universal Stop sequences telling the cell to end the protein translation and release it from the translational machinery.

KEY TO THE COLOR CODED SEQUENCES MAKING UP A GENE

Note the gene has on and off switches and rheostats that increase or decrease the level of gene activity. It has a leader sequence that “leads” the messenger to where it must go when released into the cell. It has start and stop instructions and even a signal that instructs the addition of many nucleotides of the same kind to be added to the tail of the genetic information. This “poly A site” instructs for the addition of the nucleotide “A” again and again creating a polyA tail. The length of the tail determines how long the molecule will be used in the cell to make proteins. In essence it tells the cell how many times to translate the genetic information into protein. This is one of many cellular means used to determine how much protein of each kind will be needed in the cell at any one time. Pretty cool, huh?

The messenger of DNA requires further modifications before being translated into functional proteins. A miniature ‘snip and knit’ factory called the spliceosome is required to prepare the message for use in the cell. The RED coded sequences are INTRONS or intervening sequences which may be alternately cut out of the message as the protein coding regions, GREEN, BLACK, PURPLE AND YELLOW are spliced together to form new transcripts for protein production.

So the result of alternate splicing is that the original mRNA can often be changed into a “mature” molecule of RNA ready for the cell to use in building new proteins. Now what has all of this “technobabble” to do with the differences between the genetics of chimps and that of humans?

Several researchers, including Dr. Blencowe of the Banting and Best Department of Medical Research and Department of Molecular Genetics at The University of Toronto made the comment that, “It’s clear that humans are very different from chimpanzees on several levels, but we wanted to find out if it could be the splicing process that accounts for some of these fundamental differences…The surprising thing we found was that six to eight per cent of the alternative splicing events we looked at were showing differences, which is quite significant. And those genes that showed differences in splicing are associated with a range of important processes, including susceptibility to certain diseases.” His work on the differences between the two species was recently published in the Journal of Genes and Development.

While much of Dr. Blencowe’s work is in understanding genetic diseases in humans, what he has uncovered is another layer of different molecular events that are involved in making the fertilized egg of the chimpanzee into a troglodyte and the fertilized egg of a human being into a person. The old idea that molecular biology was some kind of proof that chimps and humans where somehow related by ancestry has no bearing in reality. More and more differences are being discovered between the two kinds of creatures and at a level of molecular control once thought to be unequivocal evidence of our relatedness. There is no known chemistry by which this level of complexity arises by natural means. The fascinating differences between chimp and human genetics cannot be explained by molecular evolution. It is not that we cannot dream up a scenario where one accident led to another which led to another which made the ape. It is not that we cannot fantasize of the thousands of other molecular accidents that led an ape-like creature to give rise to a human being. What we know is that living beings develop from a single cell through the tight control of thousands of informational molecules called genes that are directed by hundreds of control signals at a level of sophistication and precision that could not be a product of nature.

Some, if not most evolutionists will continue to argue for the naturalistic but purely philosophical truth of evolution. The vast differences between species like the chimp and human are mounting and the facts of molecular biology, the heart and soul of evolution’s path to glory, is supporting a much more intelligent theory.

Even the idea that a gene has leaders, start, stop, add poly A’s here, and splicing instructions is so far beyond chance and natural selection that it is completely bewildering that anyone would give credit to evolution for the alternate instructions on the same genes that give rise to such completely different creatures such as ape and human. It does not mean we do not understand the complexity of what is happening. It means what is happening is complex beyond anything that nature could produce. These molecular events defy any form of naturally occurring process and demand that honest inquirers admit that we are not the product of chance and therefore we are not alone in the Universe. We never were. We never will be.

Such evidence demands a verdict and the verdict demands a faith. Either faith that evolution gave rise to the horrendously complex, completely fascinating processes of life through a violation of everything we know about chemical, biological and physical scientific laws, or faith which understands that within the framework of the known laws of chemistry, math, biology and physical sciences we have evidence of a creative intelligence at work in the world that goes far beyond naturally occurring events. Either way, faith is the solution. There is no way around it. The question really comes down to this – which faith makes more sense?  The choice is yours.

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