Distal control regions switch genes on and off by chromosomal folding and touching
Excerpt: "Image shows a cut-away cell nucleus (top left) with one chromosome highlighted and enlarged on the right. Each chromosome contains hundreds of genes. Enlarged section of the chromosome (bottom left) shows how chromosome folds to allow distal control regions of the DNA thread (yellow) to directly interact with a gene (blue). These distal control regions switch genes on and off. Small changes in the DNA sequence of the control regions may interfere with normal gene expression and lead to disease susceptibility.
Credit: Drs C. Varnai and P. Fraser, © The Babraham Institute 2016
My comment: There are several types of biological information in the cell. Gene sequences make a digital information platform, epigenetic layers, chemical tags and markers make an analog information layer. Chromosomal folding, 3D-genome and touching by distal control regions constitute a complex analog information layer that is very difficult to understand, measure or predict. But it tells us how the cell takes use of genes. Genes are raw library material and RNA mediated cellular processes use them along the needs of ecological adaptation. Even the slightest erroneous changes in this regulation architecture can be harmful and lead to diseases. That's why random mutations can never lead to adaptation or evolution.
