Talk:Chromatin

euchromatin and heterochromatin definitions

The current text on euchromatin and heterochromatin being equivalent to the beads on a string and 30nm fiber are wrong. The beads on a string seems to be very rare in physiological conditions and the 30nm fiber is present in both euchromatin and heterochromatin. The difference between euchromatin and (the different kinds of) heterochromatin lies in the higher order compactness. (Lodish, molecular cell biology) Kuije002 (talk) 11:52, 3 May 2012 (UTC)

Old image

Fig. 1: Levels of DNA condensation. (1) DNA double-strand helix. (2) Chromatin strand (DNA with histones). (3) Condensed chromatin during interphase with centromere. (4) Condensed chromatin during prophase. (Two copies of the DNA molecule are now present) (5) Chromosome during metaphase.

Created a new and more appropriate image showing major chromatin structures. This is the old figure.

New Image

The new image is beautiful but the simple double structure helix is left handed, where the actual structure in cells is a right handed helix. It need to be fixed.

What is polytene chromatin? My teacher asked us to define this for Genetics homework but I have been unable to find any answers and wikipedia. —Preceding unsigned comment added by Acarrell (talk • contribs) 22:13, 13 September 2007 (UTC)

Vandalism

This page seems to be getting vandalised a lot, or am I just being an anti-vandal n00b? - Zephyris _Talk 23:18, 12 December 2006 (UTC)

I agree, looking at the Chromatin and DNA repair chapter: bad English and unclear phrasing, see also my comment below...

Wolfgang WolfGreg9 (talk) 17:11, 16 July 2024 (UTC)

30nm fiber

solenoidal structure disproven

Nature 2005 436(7047):138-41 —Preceding unsigned comment added by 66.253.133.106 (talk) 18:20, 29 October 2007 (UTC)

Thanks, updated now BooleanQuackery (talk) 08:21, 31 July 2022 (UTC)

A lot of work on 30nm fiber is decently old and some newer stuff does not find evidence to support it, https://doi.org/10.1016/j.cell.2015.01.054 & 10.1126/science.aag0025 are the top two that come to mind. Maybe some context to this section that the existence of 30nm fiber is debated and at a baseline is not strictly required for packing. My recommendation is to read the papers first however. — Preceding unsigned comment added by 192.76.8.173 (talk) 12:02, 18 April 2024 (UTC)

Role of chromatin in transcription

I think this article needs to include a section emphasizing the role chromatin plays in transcription, or at least a link to a relevant section on the transcription page (which currently needs a lot of work)...MDG38 16:12, 8 November 2007 (UTC)

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Assessment comment

The comment(s) below were originally left at Talk:Chromatin/CommentsTalk:Chromatin/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

great diagram. it really helped me understand what was being said. --Jedi101 02:25, 11 December 2006 (UTC)

Last edited at 02:25, 11 December 2006 (UTC). Substituted at 11:43, 29 April 2016 (UTC)

30nm Structure - non existant ?

Hi, I was recently teaching mitosis, so looked up on condensation of chromatin. While I was browsing sources I found that some 2012 reviews / articles point towards no 30 nm structure existing - at least in mammals (fractal folding of 10 nm structure was the proposed solution). I'm wondering a) whether that is still the currently held view, and b) whether the info in this article needs updating, regardless of which model exactly is currently assumed to be most likely / best supported by the evidence.

Regards 149.172.147.203 (talk) 22:01, 18 December 2019 (UTC)

You're right, I don't know why that's stayed on the article for so long. I've deleted the content pertaining to the incorrect 30nm model, but the article still needs to be updated with current accurate models. Here's the first two results from google:

Thanks for pointing this out. I wonder if it would be possible to reincorporate the info I removed into a historical/past research section, along with the images. BooleanQuackery (talk) 08:20, 31 July 2022 (UTC)

More relevant info showing that 30 nm model is false:

The updated models should be included in this article. (It's still likely that 30 nm chromatin exists in specific rare (or transient) instances: )

BooleanQuackery (talk) 19:38, 31 July 2022 (UTC)

In my opinion the 30 nm structures shouldn't be removed outright, there are sources on them. The info on the page should be updated with later research. --Gilgul Kaful (talk) 07:23, 1 August 2022 (UTC)

Sounds good, it can be reincorporated into a historical/past research context. BooleanQuackery (talk) 09:46, 1 August 2022 (UTC)

Wiki Education assignment: Molecular Genetics

This article was the subject of a Wiki Education Foundation-supported course assignment, between 22 August 2022 and 9 December 2022. Further details are available on the course page. Student editor(s): Rgorasiya2022 (article contribs).

— Assignment last updated by Rgorasiya2022 (talk) 18:39, 4 September 2022 (UTC)

"Chromatin and DNA Repair" section

This entire section of the article requires extensive cleanup. I've fixed some of the grammar mistakes, but there are several parts of this section where I can't tell what the original author was trying to say. Unfortunately, this is not my area of expertise, so it may require rewriting by someone more familiar with the subject matter. Lumberjane Lilly (talk) 00:09, 21 April 2023 (UTC)

some quick proposals

"Structure of DNA" chapter: DNA ist located in a nucleus within the cell, not: DNA consists of a cell nucleus!! next sentence: ..of the 2 DNA strands, homogeneous H-bonds are forming. "30 nm chromatin fiber in mitosis": ..accept that the axis of DNA coiling in nucleosomes lies perpendicular.... "Chromatin and DNA repair": repairing the damaged DNA; not: repairing the damaged cell of DNA... "Methods to investigate chromatin": ChlP-seq: select, not selected; transactivation, not transaction ATAC-seq: transposon-accessible...., not transposable accessible... "Noble prizes": none have much to do with chromatin, I would omit the table. Cheers, Wolfgang WolfGreg9 (talk) 17:30, 16 July 2024 (UTC)

I agree with deleting the table. Done. Genome42 (talk) 16:37, 18 July 2024 (UTC)

"Chromatin: Alternative definitions"

Was this part AI-generated or am I just paranoid? *Diwodh₃rós (talk) 06:47, 5 March 2026 (UTC)

Probably not. There are too many grammar mistakes. E.g., the apostrophe is in the wrong place in "A biochemists'."

Either way, the alternative definitions should have sources though.

The part on chromatin remodeling seems like an advertisement and is unclear, so I will delete it.

Maybe chromatin remodeling should have a section though. Asdfaqwefvgrtwrewytre (talk) 14:09, 6 March 2026 (UTC)

Confused

This article is a prime example of confusion. If I write:" A chromatin is ..." What does this article tell us the answer is? IDK. I don't think it actually answers that. It's a "complex" (as if that should mean something other than hand-waving). No, it's a component of a "network" (which is left completely uncharacterized). It turns out, who knew, that the editors have confused the meaning of the term when used collectively with the meaning of the term when used to mean the actual structural motif of a double-stranded dna molecule (actually, a double-strand is by definition NOT a molecule (although it is widely said to be so) but a molecule-pair (in the ideal case, which ignores the other non-covalently linked (protein) components) in a cell. Clarity is needed, and it isn't provided. Also, the first several diagrams in the article PROMINENTLY display the 30-nm fiber!! As if it's accepted science. The editors choose to avoid acknowledging the FACT that it is probably an in vitro ARTIFACT by saying it "can" exist (even though many searches for it in vivo have CONSISTENTLY failed. Turns out, who knew, that absence of evidence, IS evidence of absence (if the search is reasonably thorough).) Why in the world would the editors imply it's a well-accepted structure in cells? I don't know. Why would they continually use it in the diagrams without mentioning it is likely fiction and of only very minor historical interest? I can't think of any good explanation, but a couple of bad ones. Personally, I think we have a perfectly good word to describe the dna molecule-pairs: chromosomes. ~2026-92463-4 (talk) 14:56, 9 March 2026 (UTC)

Chromatin is a substance. The word "chromatin" is a mass noun. Saying, "A chromatin is ..." is bad in the same way that saying "A gold is..."

By all means, correct any figures and paragraphs featuring in vivo 30nm fibers. Asdfaqwefvgrtwrewytre (talk) 22:39, 27 March 2026 (UTC)

@~2026-92463-4 As a biologist, I don't have citations at hand to show you, but I assure you that we use the term "chromatin" very frequently for modern science and I will try to answer all of your doubts based on my learned knowledge and experience:

1. "Chromatin" is the word we use to refer to the mixture of DNA plus proteins as it exists in living cells.
2. A "complex", in the context of cell and molecular biology, is simply a word that refers to a mixture of multiple things that functionally behave as one. In this case, the mixture is DNA + proteins. But to give you a more familiar example, ribosomes are complexes that contain two separate proteins coded by different genes, plus some RNA, yet we think of them as a single entity due to the way they function. Many important "proteins" are, in reality, protein complexes composed of subunits that are coded by separate genes.
3. Double-stranded linear DNA "molecules" are regarded as molecules in theory because they are joined by covalent bonds, namely at the telomeres, but in practice it's really because they do not separate unless under very special conditions such as high temperatures or special enzymes. They function as a unit, which is to say, a molecule. The concept of "molecule" in general is blurry the larger the size, but in the case of DNA it is universally accepted that each piece of DNA, either single- or double-stranded, is an individual molecule. Under this definition, chromatin is indeed not a molecule.
4. It is true that the 30-nm fiber is likely an artifact, but you must understand that it was not considered an artifact until very recently, and certain branches of Wikipedia are slow to update. You are welcome to make the changes yourself if you cite them appropriately.
5. A "chromosome" is an individual piece of chromatin. That is what probably confused you. Chromatin is uncountable, like sand, while chromosomes are countable, like sand grains. Often you will also see chromosomes referred to as the "individual molecules of DNA", which is true as the definition of a chromosome historically did not include the associated proteins, as they had not been discovered yet. So, chromosomes are made of chromatin, and chromatin is divided into chromosomes. They are not the same concept.

— Snoteleks (talk) 02:21, 28 March 2026 (UTC)