Chromosomes are fascinating structures. They are dynamic and highly plastic. They break under conditions of radiation or chemotoxicity, reform into a variety of new structures, and spin off small circular chromosomes called double minutes that get randomly shuffled about in the process of cell division. According to classical genetics, chromosomes are very simple molecules of a single, continuous linear DNA wrapped up within a chemical coating of protein and other molecules called chromatin. Question is, how in the world can such a simple linear molecule undergo the fantastic rearrangements known to occur within such chromosomes?
This blog provides overviews into this problem and goes into probably more detail than the average user cares to endure. For those who want the skinny without all the details or evidence, let me say this as succinctly as possible: Your chromosomes are probably incredibly more structurally complicated than classical texts would lead you to believe. Massive amounts of chromosomal DNA don’t break apart and reunite using some kind of biological black magic. There is beauty and order in how all of this is done, even when it leads to mutations, cancer, deformities, and even death. In spite of all of this, sometimes the individual gets lucky and wins the genetic lottery, leading to increased vigor and better survival. This is the very crux of what evolution is all about.
The linear chromosome advocates would have you believe that DNA mutates gradually over long periods of time, as little as one base pair at a time. Of course, this flies in the face of overwhelming evidence that chromosomes can be broken up like shattering glass and reformed into an endless variety of “new” chromosomes. Surely, over time, some of these rearrangements can prove harmless, even beneficial to the recipient. However, such gross rearrangements may involve millions of base pairs of DNA. How can such massive rearrangements occur in a simple linear DNA model? Imagine breaking a 50,000 micron strand in the middle within a six micron diameter cell nucleus and trying to turn one piece completely around and rejoin it with the other.
If this piques your interest and you have some time, pore over some of this blog to see what I am talking about. Skip any sections that are too involved and just go on to the next one. You can learn a lot just by doing that. You may also write me by e mail for additional information or write comments. This is an open forum and I welcome any and all constructive input: firstname.lastname@example.org.