Euchromatin and Heterochromatin (Constitutive vs Facultative) | Chromatin Regulation

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Instructor: Dave Carlson
DNA - Histones 2 - Issues from tightly packed DNA
Heterochromatin & Euchromatin

[@Pseudify]

I think there was an error said at 2:19. He said constitutive heterochromatin wouldn't be replicated or translated. I think he meant to say it wouldn't be *transcribed* or translated. Replication is just the copying of DNA which happens for ALL chromatin - otherwise, if it's not replicated it wouldn't be there in the first place. Otherwise, this a very good video!

[@gregorykarimian3813]

exactly! transcription and translation = expression. replication is something entirely different. heterochromatin needs to be replicated, otherwise a daughter cell will be missing lots of chromosome.

[@M.e.d.c.i.n.e]

Thaaank u

[@alive680]

Thanks God I found your video Finally I understood something ! Thank you so much

[@louisadu-amoah1504]

Excellent. So clean, clear and simple to grasp

[@arok2606]

Very easy to understand explanation, thank you!

[@gabiroman8910]

am i the only one getting distracted by how handsome the teacher is? like,after 10 seconds i relised i was not focusing and I had to start again.

[@ashwin88able]

you need to re-evaluate your career choices. smh…

[@samamso2155]

thank you very much.

[@Jere616]

Very good.

[@kendall2004]

tysm😊

[@almernzenwa3127]

Very easy to understand

[@ilianadjmabadi1704]

Very clear

[@farishkhan7157]

Can u explain me why it is inactive through out the life

[@qwevasdef9285]

What's the point of constitutive heterochromatin? How is it useful if you can't translate nor transcribe it?

[@isaiah9322]

some genes within DNA are never meant to be expressed, but are unable to be removed. thus they are kept so tightly wound that they remain inaccessible permanently. the reasons for which they don't want to be expressed can be as simple as its an inherited trait during the cell cycle or that it evolved to be that way.

[@kautharmumin3006]

I though that it was cytosine on the DNA molecule that would be methylated or unmethylated

[@Bagna1996]

Sure and I thought that the whole genome was replicated not only euchromatin and facultative heterochromatin🤭😅

[@Pseudify]

Cytosine is often methylated, but so are histones (typically on + amino acids).

[@leenmcheik7862]

@@Bagna1996 it's all replicated

[@GreatUncleBuck]

If most of the DNA will never be expressed in specific cells why are the complete Genome replicated to all cells and continued to be replicated. Is that not highly ineffective w.r.t. energy required to perform activities even on parts of the DNA that will never be used during the life of different cells?

[@isaiah9322]

no its benign because when transcription occurs, not the entire molecule of DNA is opened up. the RNA polymerase follows a "bubble" of opened DNA (only about 10 base pairs long) that will close shortly after the polymerase transcribes that portion of the gene. this is energy efficient because cells need the entire genome because certain genes on the DNA will be on "opposite ends" and thus if the DNA were to be shortened, the cell would be missing out on needed instructions.