How does DNA methylation affect chromatin structure?
DNA methylation inhibits gene expression in animal cells, probably by affecting chromatin structure. Biochemical studies suggest that this process may be mediated by methyl-specific binding proteins that recruit enzymatic machinery capable of locally altering histone modification.
What is chromatin and euchromatin?
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.
How is the structure of chromatin related to gene expression?
Chromatin structure plays a key role in regulating gene expression by allowing DNA accessibility to transcriptional machinery and transcription factors [12].
Which molecules are present in chromatin?
Chromatin is the material that makes up a chromosome that consists of DNA and protein. The major proteins in chromatin are proteins called histones.
Does acetylation condense chromatin?
Acetylated histones, octameric proteins that organize chromatin into nucleosomes basic structural unit of the chromosomes and ultimately higher order structures, represent a type of epigenetic marker within chromatin. Condensation can be brought about by processes including deacetylation and methylation.
How do you distinguish between euchromatin and heterochromatin?
Difference Between Euchromatin and Heterochromatin
| Euchromatin | Heterochromatin |
|---|---|
| Appear as a loose packed form of DNA | Appear as tight packed form of DNA |
| Heteropycnosis is not shown | Exhibits Heteropycnosis |
| DNA density is low | High density of DNA is present |
| Present in prokaryotes and Eukaryotes | Available in Eukaryotes only |
Why is euchromatin more transcriptionally active?
In prokaryotes, euchromatin is the only form of chromatin present; this indicates that the heterochromatin structure evolved later along with the nucleus, possibly as a mechanism to handle increasing genome size.
How do chromatin remodelers change the structure of the chromatin?
In contrast to histone modifications, which do not require energy, chromatin remodeling is an energy-driven process in which chromatin remodelers use the energy of ATP hydrolysis to change the nucleosome structure [49, 50]. After DNA replication, chromatin remodelers pack genomic DNA into nucleosomes.
What is the first order of chromatin packing?
The first level of packing is achieved by the winding of DNA around a protein core to produce a “bead-like” structure called a nucleosome. This gives a packing ratio of about 6. This structure is invariant in both the euchromatin and heterochromatin of all chromosomes.