is this right

[pistolpete007]

exons and introns will be transcribed into mRNA....however only exon will be translated


euchromitins will be transcribe and then translated

heterochromitin---will NOT get transcribed to mRNA

polytene are euchromitns in earliar state that are heterochromitn later

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[osimsDDS]

These are all forms of gene expression and regulation in eukaryotes...

First of all it is to be noted that pre-mRNA has introns and exons along with 5'UTR and 3'UTR region, the mRNA then undergoes RNA processing which splices out the introns and leaves the exons for translation (the functional genes) as well as addition of a poly A tail and also 5' GTP cap. After this the mRNA leaves the nucleus into the cytoplasm where it will get translated into protien...

So now euchromatin and heterochromatin are ways for eukaryotes to regulate transcription. The heterochromatin is heavily methylated and is very tightly packed by histones into the nucleosome form while the euchromatin is less packed because of acetylation...Therefore these "flimsy" euchromatin can undergo transcription of that particular gene that codes for a particular protein...

And polytene is basically when a cell undergoes DNA division in the cell without undergoing mitosis to increase the chances of transcription...

HOPE THAT HELPS!!!

 

[pistolpete007]

that does help but now im kind of confused over methylation and demethylation.....on schaums question 10.9 it asked

How was the methylation of cytosine been implicated in the initiation of transcription?

it said: Marked demethylation occurs in areas of transcription. it is believed that methyl groups influence the conformation of DNA and, thus, that changes in methylation produce corresponding changes in DNA conformation that affect the ability of regulators to bind the DNA>

so the question syas methylation is what initiates transcription

and from the answer i got demethylation causes transcription....or thats what im getting out of it can u allaborate on this please

 

[osimsDDS]

from what I know (cliffs AP bio) it says that demethylation or acetylation causes the euchromatin to attach loosely to DNA and that is where transcription factors can bind...i have read schaum's also and came across the same problem but I think schaum's is saying it in a way thats hard to understand. Cliffs put it straight forward, high methylation = heterochromatin = tightly bound little transcription. Less methylation, or acetylation occurs on euchromatin making it less tightly bound and more probability for trascription factors to bind and start transcription...

Thats just what I know someone else can prob correct me or back me up on it