DNA Structure and Replication

ID #1706

Does the DNA double helix need to be separated from the histones and the non-histone proteins in order for the DNA to be denatured, replicated, or transcribed? If yes, does this mean that most of the 30 nm fibers of euchromatin in interphase are not being replicated?

There are some things that the cell does with its DNA which it can do while working around the histones -- in other words, the nucleosomes don't have to be disassembled. Other things involve repositioning the existing nucleosomes temporarily. And still others involve disassembly of histone complexes. Replication would be an example of the latter, and if we take this one step further, it makes sense. Recall that parental DNA does not come back together when replicated, so original nucleosomes cannot possibly remain intact. And also consider that when replication is complete, you'll have twice the amount of DNA but the same number of histone proteins. Unless you make more histone proteins to keep up, and create new nucleosomes, which is exactly what happens.

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