Chromatin

chromatin structuresex chromatinnuclear chromatinchromatinechromatinizednucleic acid-protein complexeschromaticchromatin conformationchromatin domainschromatin organization
Chromatin is a complex of DNA and protein found in eukaryotic cells.wikipedia
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DNA

deoxyribonucleic aciddouble-stranded DNAdsDNA
Chromatin is a complex of DNA and protein found in eukaryotic cells.
Within eukaryotic chromosomes, chromatin proteins, such as histones, compact and organize DNA.

Chromosome

chromosomeschromosomalChromosomal number
During mitosis and meiosis, chromatin facilitates proper segregation of the chromosomes in anaphase; the characteristic shapes of chromosomes visible during this stage are the result of DNA being coiled into highly condensed networks of chromatin.
The term was coined by the German scientist von Waldeyer-Hartz, referring to the term chromatin, which was itself introduced by Walther Flemming, who discovered cell division.

DNA repair

DNA damagerepairtranslesion synthesis
Its primary function is packaging very long DNA molecules into a more compact, denser shape, which prevents the strands from becoming tangled and plays important roles in reinforcing the DNA during cell division, preventing DNA damage, and regulating gene expression and DNA replication.
Nuclear DNA (nDNA) exists as chromatin during non-replicative stages of the cell cycle and is condensed into aggregate structures known as chromosomes during cell division.

Euchromatin

euchromatic
Regions of DNA containing genes which are actively transcribed ("turned on") are less tightly compacted and closely associated with RNA polymerases in a structure known as euchromatin, while regions containing inactive genes ("turned off") are generally more condensed and associated with structural proteins in heterochromatin.
Euchromatin is a lightly packed form of chromatin (DNA, RNA, and protein) that is enriched in genes, and is often (but not always) under active transcription.

Nucleosome

nucleosomesnucleosome core particlenuclesome
Nucleosomes form the fundamental repeating units of eukaryotic chromatin, which is used to pack the large eukaryotic genomes into the nucleus while still ensuring appropriate access to it (in mammalian cells approximately 2 m of linear DNA have to be packed into a nucleus of roughly 10 µm diameter).

Mitosis

mitoticmitosesmitotic division
During mitosis and meiosis, chromatin facilitates proper segregation of the chromosomes in anaphase; the characteristic shapes of chromosomes visible during this stage are the result of DNA being coiled into highly condensed networks of chromatin.
During interphase, the genetic material in the nucleus consists of loosely packed chromatin.

Spermatozoon

spermatozoaspermsperm cells
For example, spermatozoa and avian red blood cells have more tightly packed chromatin than most eukaryotic cells, and trypanosomatid protozoa do not condense their chromatin into visible chromosomes at all.
The specimen contributes with DNA/chromatin, a centriole, and perhaps also an oocyte-activating factor (OAF).

Histone

histoneshistone modificationhistone modifications
Histone proteins are the basic packer and arranger of chromatin and can be modified by various post-translational modifications to alter chromatin packing (Histone modification).
They are the chief protein components of chromatin, acting as spools around which DNA winds, and playing a role in gene regulation.

Polycomb-group proteins

PolycombPolycomb groupPolycomb-group
Polycomb-group proteins play a role in regulating genes through modulation of chromatin structure.
Polycomb-group proteins are a family of protein complexes first discovered in fruit flies that can remodel chromatin such that epigenetic silencing of genes takes place.

Acetylation

acetylateddeacetylationN-terminal acetylation
Epigenetic modification of the structural proteins in chromatin via methylation and acetylation also alters local chromatin structure and therefore gene expression.
Among these proteins, chromatin proteins and metabolic enzymes are highly represented, indicating that acetylation has a considerable impact on gene expression and metabolism.

Gene expression

expressionexpressedexpress
Its primary function is packaging very long DNA molecules into a more compact, denser shape, which prevents the strands from becoming tangled and plays important roles in reinforcing the DNA during cell division, preventing DNA damage, and regulating gene expression and DNA replication.
In eukaryotes the structure of chromatin, controlled by the histone code, regulates access to DNA with significant impacts on the expression of genes in euchromatin and heterochromatin areas.

DNA condensation

chromosome condensationcondensationcondense
Its primary function is packaging very long DNA molecules into a more compact, denser shape, which prevents the strands from becoming tangled and plays important roles in reinforcing the DNA during cell division, preventing DNA damage, and regulating gene expression and DNA replication.
Most of the time, between cell divisions, chromatin is optimized to allow easy access of transcription factors to active genes, which are characterized by a less compact structure called euchromatin, and to alleviate protein access in more tightly packed regions called heterochromatin.

Nuclear lamina

laminalamin
Territories are, for example, the lamina-associated domains (LADs), and the topologically associating domains (TADs), which are bound together by protein complexes.
Additionally, it participates in chromatin organization and it anchors the nuclear pore complexes embedded in the nuclear envelope.

Heterochromatin

heterochromaticfacultative heterochromatin30nm structure of chromatin
Regions of DNA containing genes which are actively transcribed ("turned on") are less tightly compacted and closely associated with RNA polymerases in a structure known as euchromatin, while regions containing inactive genes ("turned off") are generally more condensed and associated with structural proteins in heterochromatin.
Chromatin is found in two varieties: euchromatin and heterochromatin.

Chromatin remodeling

chromatin remodelerschromatin remodellingremodeled
In eukaryotes, ATP dependent chromatin remodeling complexes and histone-modifying enzymes are two predominant factors employed to accomplish this remodeling process.
Chromatin remodeling is the dynamic modification of chromatin architecture to allow access of condensed genomic DNA to the regulatory transcription machinery proteins, and thereby control gene expression.

Bookmarking

Mitotic bookmarking
During mitosis, gene transcription is silenced and most transcription factors are removed from chromatin.

PARP1

PARP-1PARPPoly (ADP-ribose) polymerase 1
This process is initiated by PARP1 protein that starts to appear at DNA damage in less than a second, with half maximum accumulation within 1.6 seconds after the damage occurs.
PARP1 contributes to repair efficiency by modulating chromatin structure and by interacting with and modifying multiple DNA repair factors.

Spermiogenesis

spermiationmanchette
During metazoan spermiogenesis, the spermatid's chromatin is remodeled into a more spaced-packaged, widened, almost crystal-like structure.
The resultant tightly packed chromatin is transcriptionally inactive.

Gene

genesnumber of genesgene sequence
The local structure of chromatin during interphase depends on the specific genes present in the DNA.
DNA packaged and condensed in this way is called chromatin.

Chromosome conformation capture

Hi-C3C and 4CHi-C (experiment)
Chromosome conformation capture techniques (often abbreviated to 3C technologies or 3C-based methods ) are a set of molecular biology methods used to analyze the spatial organization of chromatin in a cell.

ATAC-seq

assay for transposase-accessible chromatin using sequencing
ATAC-seq (Assay for Transposase-Accessible Chromatin using sequencing) is a technique used in molecular biology to assess genome-wide chromatin accessibility.

Cell nucleus

nucleusnucleinuclear
This process is associated with the cessation of transcription and involves nuclear protein exchange.
Lamin structures that make up the veil, such as LEM3, bind chromatin and disrupting their structure inhibits transcription of protein-coding genes.

Karyotype

karyotypingkaryogramFN
There is variation between species in chromosome number, and in detailed organization, despite their construction from the same macromolecules.

H2AFX

H2AXgammaH2AXH2A.X
γH2AX, the phosphorylated form of H2AX is also involved in the early steps leading to chromatin decondensation after DNA damage occurrence.
In humans and other eukaryotes, the DNA is wrapped around histone octamers, consisting of core histones H2A, H2B, H3 and H4, to form chromatin.

Spermatid

spermatidselongating spermatid
During metazoan spermiogenesis, the spermatid's chromatin is remodeled into a more spaced-packaged, widened, almost crystal-like structure.
The resultant tightly packed chromatin is transcriptionally inactive.