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The position of CENPA within satellite DNA are heritable at the protein level through a purely epigenetic mechanism. [17] This means that the position of CENPA protein binding to the genome is copied upon cell division to the two daughter cells independent of the underlying DNA sequence.
Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. Satellite DNA is the main component of functional centromeres , and form the main structural constituent of heterochromatin .
Nucleosome core particles are observed when chromatin in interphase is treated to cause the chromatin to unfold partially. The resulting image, via an electron microscope, is "beads on a string". The string is the DNA, while each bead in the nucleosome is a core particle. The nucleosome core particle is composed of DNA and histone proteins. [29]
Alphasatellites are a single-stranded DNA family of satellite viruses that depend on the presence of another virus (helper viruses) to replicate their genomes. As such, they have minimal genomes with very low genomic redundancy. The genome is a single circular single strand DNA molecule. [1]
An acentric chromosome is fragment of a chromosome that lacks a centromere. Since centromeres are the attachment point for spindle fibers in cell division, acentric fragments are not evenly distributed to daughter cells during cell division. As a result, a daughter cell will lack the acentric fragment and deleterious consequences could occur.
The name derives from the small chromosomal segment behind the secondary constriction, called a satellite, named by Sergei Navashin, in 1912. [5] Later, Heitz (1931) qualified the secondary constriction as the SAT state ( Sine Acido Thymonucleinico , which means "without thymonucleic acid"), because it didn't stain with the Feulgen reaction .
Centromeres are composed of a 177 base pair tandem repeat named the α-satellite repeat. [16] Pericentromeric heterochromatin, the DNA which surrounds the centromere and is important for structural maintenance, is composed of a mixture of different satellite subfamilies including the α-, β- and γ-satellites as well as HSATII, HSATIII, and ...
However, in order for the cell to function, proteins must be able to access the sequence information contained within the DNA, in spite of its tightly-packed nature. Hence, the cell has a number of mechanisms in place to control how DNA is organized. [4] Moreover, nuclear organization can play a role in establishing cell identity.