Are genes transcribed just as well when chromosomes are condensed?

I want to design a screen that depends on genes not transcribed when chromosomes are condensed (to identify cells that can't condense).

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    $\begingroup$ I think you are going to need to add a little more detail than this. Do you mean condensed like metaphase condensed, or do you just mean genes normally found in heterochromatic regions of the nucleus? If the latter, then you will want specify the cell type you are thinking of using as different cell types will have different genes silenced in heterochromatin and accessible in euchromatin. A lot of it has to do with the transcription factors reaching the nucleus and also chromatin remodeling complexes. some heterochromatin is more accessible than others. $\endgroup$ – AMR Oct 18 '15 at 4:35

The compaction of DNA into chromatin is a very complex process that involves not only DNA, but on the histone code. Some may say that the histone code plays more of a role in chromatin state To develop a screen you would have understand the act of methylation, acetylation, ubiquitination, and phosphorylation of all modifiable histone residues. The modification of histone residues determine if the chromatin is in a heterochromatin or euchromatin state and even in which sections of DNA are accessible and transcriptionally active.

It is also important to note that the same modification of any of the 8 histone proteins in any nucleosome (the fundamental unit of chromatin) may not produce the same result.

For example: The methylation of H2 histone in the first nucleosome of a chromatin "string" may cause silencing while the methylation of H2 histone further down the chromatin "string" may cause activation.

It's alot of information but maybe one day you will be the one who solves the pattern! It sure is fascinating.

  • $\begingroup$ @cagliari2005 I think that you may need to review your histone tail modifications, which can undergo Methylation, Phosphorylation, Acetylation and Ubiquitination and those modifications are on the Proteins, not on the DNA. And the "string" reference is referring to the "Beads on a String" fiber that is the first level (and only confirmed) of DNA compaction. It yields the 100 Angstrom fiber. And while neither question nor answer is worded that well, I think both users know at least the proper use of the vocabulary. The OPs other question is about mitotic arrest in yeast. $\endgroup$ – AMR Oct 18 '15 at 14:05

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