Genome complexity: packing DNA requires design (Introduction)

by David Turell , Thursday, September 09, 2021, 01:32 (961 days ago) @ David Turell

Six feet coiled into a tiny space:

https://evolutionnews.org/2021/09/hierarchical-systems-in-biology-dna-packaging/

"So how do you package one meter of information content into a space 1/100,000 that size? Very carefully and quite ingeniously. The storage of DNA is very much like hierarchical file systems on Windows and Linux desktop computers compressed into a .zip file. In the same manner that there are folders within folders within folders in a desktop computer, with the actual files at the terminal level, individual genes within a DNA molecule are equivalent to “files” that in this case specify the building of a protein needed for the cell to function. DNA packaging is far more complex, however, with several levels of packaging into a highly compressed and compact structure called chromatin. Essentially, there are three orders of DNA packaging: the first order is the nucleosome, the second order is the solenoid fiber, and the third order is the scaffold loop chromatids chromosome. The diagram below demonstrates the levels of packaging.

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"The first level of packaging of DNA is where the double-stranded DNA is wrapped around spools of histone, a family of positively charged proteins that function primarily in packaging DNA, to form nucleosomes, creating the appearance of “beads” on a string. The nucleosomes themselves are then coiled into a 10 nm (10 billionths of a meter) fiber. Each nucleosome “core” consists of eight histone molecules. The nucleosomes are then further folded into the second order supercoiled solenoid fiber, which is 30 nm in width. The third order is the forming of looped domains of solenoid fibers that average 300 nm in width which are then further compressed down to 250 nm to form chromatin fiber. The chromatin fibers are further folded into 700 nm chromatids, and finally we have the highest order of structure that forms the characteristic shape of a chromosome which is 1400 nm in width as seen above.

It is hard to fathom that such a highly complex, hierarchical mechanism of information storage on a microscopic scale could come about purely by chance, which more importantly demonstrates a clear case of the classic “chicken and egg” problem. This complex, highly orchestrated packaging model, coordinated by the machinery of enzymes (topoisomerases) and various types of histones that are proteins themselves coded in DNA, must have come prior to DNA and prior to the random variation mechanism of evolution itself. The DNA packaging model is programmed with the knowledge of what regions of the chromosome to keep tightly supercoiled and what regions to keep more loosely packed to aid in DNA transcription. Moreover, if a region needed for transcription is supercoiled, it will unwind that region and compensate for the unwinding with a compensating supercoil in a prior region. Thus, there is an astounding process of coordination taking place within the process of transcribing DNA.

"Interestingly, there are companies that recognize the genius of DNA and its packaging model who are investigating using DNA molecules as a means of creating molecular-level archival data storage to solve the problem of an ever-increasing amount of digital data that is surpassing the amount of physical storage available using modern magnetic and optical media. For example, tech giant Microsoft is currently engaged in this research, noting the following on their website: “Using DNA to archive data is an attractive possibility because it is extremely dense (up to about 1 exabyte per cubic millimeter) and durable (half-life of over 500 years).” When one considers the fact that the world’s finest software engineers look to the DNA packaging topology to dramatically increase storage capability by orders of magnitude, it is reasonable to conclude that the packaging and processing of DNA is the product of a purposeful designer with a degree of engineering knowledge simply unmatched by humans."

Comment: When humans look to how DNA works for computer ideas, it is obvious a designer wass at work to create it.