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The major structures in DNA compaction: DNA, the nucleosome, the 11 nm beads on a string chromatin fibre and the metaphase chromosome. Chromatin is a complex of DNA and protein found in eukaryotic cells. [1] The primary function is to package long DNA molecules into more compact, denser structures.
The solenoid structure's most obvious function is to help package the DNA so that it is small enough to fit into the nucleus. This is a big task as the nucleus of a mammalian cell has a diameter of approximately 6 μm, whilst the DNA in one human cell would stretch to just over 2 metres long if it were unwound. [6]
Eukaryotic chromosome structure refers to the levels of packaging from raw DNA molecules to the chromosomal structures seen during metaphase in mitosis or meiosis. Chromosomes contain long strands of DNA containing genetic information. Compared to prokaryotic chromosomes, eukaryotic chromosomes are much larger in size and are linear chromosomes.
Chromosome scaffold has important role to hold the chromatin into compact chromosome. Chromosome scaffold is made of proteins including condensin, topoisomerase IIα and kinesin family member 4 (KIF4) [7] Dinoflagellates are very divergent eukaryotes in terms of how they package their DNA. Their chromosomes are packed in a liquid-crystalline ...
Organization of DNA in a eukaryotic cell. Each eukaryotic chromosome consists of a long linear DNA molecule associated with proteins, forming a compact complex of proteins and DNA called chromatin. Chromatin contains the vast majority of the DNA in an organism, but a small amount inherited maternally can be found in the mitochondria.
In contrast to most eukaryotic cells, mature sperm cells largely use protamines to package their genomic DNA, most likely to achieve an even higher packaging ratio. [17] Histone equivalents and a simplified chromatin structure have also been found in Archaea, [18] suggesting that eukaryotes are not the only organisms that use nucleosomes.
Researchers studied eukaryotic evolutionary lineages of histone proteins and found diversification among the regulatory genes. The greatest differences were observed in core histone gene cis-regulatory sequence motifs and associated protein factors. Variability in gene sequence was seen in bacterial, fungi, plant, and mammalian genes. [10]
The organization of chromosomes into distinct regions within the nucleus was first proposed in 1885 by Carl Rabl.Later in 1909, with the help of the microscopy technology at the time, Theodor Boveri coined the termed chromosome territories after observing that chromosomes occupy individually distinct nuclear regions. [6]