Traits are not determined by gene sequences - Epigenetic information layer is used for cellular differentiation
Each of our cells has the same gene sequences. However, there are hundreds of different cell types in our bodies. By which mechanism is a skin cell specialized into its own function? Why does a nerve cell have its own identity? Hundreds of different cell types are capable of producing hundreds of thousands of different proteins even though they have the same gene sequences. How is this possible?
There are several forms of biological information in our cells. Gene sequences constitute a digital body and a platform for other forms of biological information. For their successful differentiation, the cells need a specific information layer that functions on top of the genes. This kind of information is called epigenetic control of gene expression. If the epigenetic information layer is removed from the cell, it becomes a pluripotent stem cell that is in an open state to specialize in any task. Our genome has only about 19,600 protein encoding genes, but different proteins in our bodies are up to one million. Epigenetic control of gene expression and transcription makes this possible.
An epigenetic data structure consists mainly of chemical markers on top of genes. The most significant epigenetic marking of DNA is a methyl group (CH3) attached to a cytosine base. Also, methylation of DNA packaging proteins, i.e. histones, greatly affects the identity of the cell and the structure of the protein it produces. The number of different epigenetic markers on the DNA is not so high compared to RNA, whose epigenetic markers science has only started to understand in recent years. There are over a hundred different epigenetic markers of the RNA and they have a significant effect on protein production and embryonic development. Long and short non-coding RNA molecules form a significant group of epigenetic regulatory elements that participate in many vital regulatory tasks in our body.
The cell uses epigenetic information for many different functions. Genes can be suppressed, silenced or activated by methylating certain regions of them. The number of methyl groups in a gene and its different regions also plays a decisive role in the type and quality of the cell-produced protein. There are also genes in which only one addition or deletion of one methyl group has a significant influence on cell activity and identity. About 95% of plant genes are epigenetically suppressed, which explains their enormous potential for variation.
Perhaps the most interesting feature of epigenetic information is its analog nature. The team of McGill researchers, led by Professor Moshe Szyf of the Department of Pharmacology and Therapeutics, and Professor Ehab Abouheif, from the Department of Biology, found that the size of the Florida Carpenter Ants changed based on the amount of DNA methylation of a certain gene. Thus, the amount of methylation in the gene can act as a control knob, such as a volume regulator.
An example of epigenetic control of gene expression: Skin color.
If skin cells are programmed to produce white pigment instead of black, then which one is being changed, the gene sequences or the epigenome? The correct answer is: the epigenome.
This fact has been studied only by a few scientists, because it’s too inconvenient fact for the theory of evolution. Here’s one example:
Unfortunately this group doesn’t realize that point mutations don’t modulate methylation patterns or levels on genes and histones. It’s done by non coding RNA molecules.
Others have tried to find the reason for human skin color variation by examining sequence changes with poor results. They claim that light skin is determined by sequence changes in SLC45A2 gene, but do they tell that this claimed mutation is nearly absent in East Asia? So, they try to use another pseudoscientific explanation: Convergent evolution. This is the level of population genetics. It’s false science.
There is no such a thing as mutation driven evolution or different human races. We all are created by loving God. Don’t get misled.