Related Experiment Video
Updated: Aug 15, 2026
11:04
A Cell Free Assay to Study Chromatin Decondensation at the End of Mitosis
Published on: December 19, 2015
The eukaryote chromosome, a two-state system with interconversion by a volume phase transition
Andrew J Beel1, Pierre-Jean Matteï1, Roger D Kornberg1
1Department of Structural Biology, Stanford University, Stanford, CA, USA.
Science (New York, N.Y.)
|August 13, 2026
Summary
Eukaryotic chromosomes are ionic hydrogels that undergo volume phase transitions, similar to liquid-gas transitions, to condense and decondense. Histone acetylation and deacetylation control this process, impacting chromatin structure.
Area of Science:
- Molecular Biology
- Biophysics
- Genetics
Background:
- Chromosome condensation is essential for cell division.
- Condensins facilitate loop extrusion, reducing chromosomal length.
- The mechanism behind increased chromatin density during condensation remains unclear.
Purpose of the Study:
- To investigate the physical properties of eukaryotic chromosomes.
- To elucidate the mechanism driving chromatin condensation and decondensation.
- To explore the role of ionic interactions and histone modifications in regulating chromosomal states.
Main Methods:
- Characterization of chromosomal material as an ionic hydrogel.
- Analysis of the chromosomal material as a two-state system.
- Investigation of volume phase transitions analogous to liquid-gas transitions.
Main Results:
- Eukaryotic chromosomes function as ionic hydrogels.
- Chromosomal material exhibits a two-state system with reversible transitions.
- Ionic contacts between histone tails and DNA, modulated by acetylation/deacetylation, control condensation/decondensation.
Conclusions:
- Chromosomal condensation is driven by a volume phase transition in an ionic hydrogel system.
- Histone acetylation and deacetylation are key regulators of chromatin condensation and decondensation.
- This model explains condensation in heterochromatin and decondensation in euchromatin.
Related Concept Videos
01:01Euchromatin
The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions take up more dye, appearing darker, while the less-compact areas take up less dye and appear lighter. Based on the compaction level, chromatins are classified into two primary forms – euchromatin and heterochromatin.
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
01:01Euchromatin
The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions take up more dye, appearing darker, while the less-compact areas take up less dye and appear lighter. Based on the compaction level, chromatins are classified into two primary forms – euchromatin and heterochromatin.
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
02:40Chromosome Structure
A functional eukaryotic chromosome must contain three elements: a centromere, telomeres, and numerous origins of replication.
The centromere is a DNA sequence that links sister chromatids. This is also where kinetochores, protein complexes to which spindle microtubules attach, are constructed after the chromosome is replicated. The kinetochores allow the spindle microtubules to move the chromosomes within the cell during cell division.
Telomeres consist of non-coding repetitive nucleotide...
The centromere is a DNA sequence that links sister chromatids. This is also where kinetochores, protein complexes to which spindle microtubules attach, are constructed after the chromosome is replicated. The kinetochores allow the spindle microtubules to move the chromosomes within the cell during cell division.
Telomeres consist of non-coding repetitive nucleotide...
02:40Chromosome Structure
A functional eukaryotic chromosome must contain three elements: a centromere, telomeres, and numerous origins of replication.
The centromere is a DNA sequence that links sister chromatids. This is also where kinetochores, protein complexes to which spindle microtubules attach, are constructed after the chromosome is replicated. The kinetochores allow the spindle microtubules to move the chromosomes within the cell during cell division.
Telomeres consist of non-coding repetitive nucleotide...
The centromere is a DNA sequence that links sister chromatids. This is also where kinetochores, protein complexes to which spindle microtubules attach, are constructed after the chromosome is replicated. The kinetochores allow the spindle microtubules to move the chromosomes within the cell during cell division.
Telomeres consist of non-coding repetitive nucleotide...
01:34Crossing Over
Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where each chromosome—replicated in S phase—is now composed of two sister chromatids (identical copies) joined centrally.
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
01:30Crossing Over
Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I, duplicated...