Immunity system complexity: packing DNA (Introduction)

by David Turell , Monday, January 17, 2022, 19:24 (824 days ago) @ David Turell

At six feet long it must be packed for cell division in a way that it will not be damaged by cell splitting:

https://www.sciencedaily.com/releases/2022/01/220113151434.htm

"Threads or earphone cables placed in tight spaces get easily tangled. On the contrary, our body's long and loose DNA packs into rod-shaped chromosomes one-millionth its size when the cell divides. If cell division occurs with DNA that is almost two meters in length, there is the risk of damage or loss in genetic information. Therefore, the condensation of chromosomes is essential to accurately transmitting genetic information.

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"The packing mechanism that condenses the chromosomes into one-millionth its size without any tangling and the 3D structure that enables this have puzzled researchers for over a half a century. However, it has been difficult to observe the chromosomes in their native condition. The researchers had to resort to detecting only some components of the chromosomes or infer their condensed state from looking at their uncoiled state.

"This study verified the 3D structure of chromosomes by using coherent X-rays generated from the 3rd generation synchrotron facility after rapidly freezing the hydrated chromosomes and maintaining them in a cryogenic state. This is the research that uncovered the structure of the chromosomes in native states, unlike conventional techniques that thinly cut or dyed them.

"Through the study, the research team confirmed that the chromosomes were formed in a fractal structure rather than the hierarchical structure stated in previous studies. In addition, a physical model showing the packing process of chromosomes was presented."

Comment: following a fractal formula is simply repeating the same basic pattern over and over in a branching system. Not likely natural forces found this solution which had to be present with the first bacteria formed. Since cell division is constantly happening to keep tissues fresh, this vital system must work correctly to preserve genome integrity, avoiding errors which will cause diseases by mistakes. Not yet described but obviously necessary are the multiple shepherding molecules acting automatically at nanosecond speed.