Is heterochromatin easily transcribed?
Is heterochromatin easily transcribed?
Heterochromatin is densely packed and inaccessible to transcription factors so it is rendered transcriptionally silent (Richards and Elgin 2002).
How is heterochromatin more frequently transcribed than euchromatin?
Euchromatin is transcriptionally-active. Heterochromatin has more amount of DNA tightly compressed with the histone proteins. Euchromatin has less amount of DNA lightly compressed with the histone proteins.
Is euchromatin always acetylated?
Heterochromatin contains acetylated H4 (except H4Ac8) during and (shortly) after replication; euchromatin, too, is most strongly acetylated during replication; the NOR contains acetylated H4 during mitosis, as do nucleoli in G1 and G2, but during S phase the histone H4 acetylation within nucleoli is considerably …
How much does heterochromatin cost?
In humans these regions account for about 200Mb or 6.5% of the total human genome, but their repeat composition makes them difficult to sequence, so only small regions have been sequenced.
How does chromatin remodeling occur?
Such remodeling is principally carried out by 1) covalent histone modifications by specific enzymes, e.g., histone acetyltransferases (HATs), deacetylases, methyltransferases, and kinases, and 2) ATP-dependent chromatin remodeling complexes which either move, eject or restructure nucleosomes. …
How is euchromatin different from heterochromatin?
Heterochromatin and euchromatin are two major categories of chromatin higher order structure. Heterochromatin has condensed chromatin structure and is inactive for transcription, while euchromatin has loose chromatin structure and active for transcription.
Why is euchromatin more transcriptionally active?
The key distinction between the structure of euchromatin and heterochromatin is that the nucleosomes in euchromatin are much more widely spaced, which allows for easier access of different protein complexes to the DNA strand and thus increased gene transcription.
Why is heterochromatin at Rich?
Some scientific articles show that Giemsa doesn’t interact with DNA-related histones. During karyotyping or R-banding, the dark segments of a chromosome construct heterochromatin and they are rich in A and T, while the clear segments constructs euchromatin and they are rich in G and C.
Can heterochromatin be replicated?
Replication of heterochromatic DNA occurs late during S phase. Because it remains highly compacted throughout the cell cycle, it has been unclear how the replication machinery can proceed through such a formidable barrier.
