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"Point centromeres" bind to specific proteins that recognize particular DNA sequences with high efficiency. Any piece of DNA with the point centromere DNA sequence on it will typically form a centromere if present in the appropriate species. The best characterized point centromeres are those of the budding yeast, Saccharomyces cerevisiae ...
The human homolog, hsSgo1, associates with centromeres during prophase and disappears when anaphase starts. [74] When Shugoshin levels are reduced by RNAi in HeLa cells, cohesin cannot remain on the centromeres during mitosis, and consequently sister chromatids separate synchronically before anaphase initiates, which triggers a long mitotic arrest.
Bottom: Two tomato SCs with the chromatin removed, allowing kinetochores ("ball-like" structures) at centromeres to be revealed. The synaptonemal complex ( SC ) is a protein structure that forms between homologous chromosomes (two pairs of sister chromatids ) during meiosis and is thought to mediate synapsis and recombination during prophase I ...
In prophase of mitosis, specialized regions on centromeres called kinetochores attach chromosomes to spindle fibers. The monocentric chromosome is a chromosome that has only one centromere in a chromosome and forms a narrow constriction. Monocentric centromeres are the most common structure on highly repetitive DNA in plants and animals. [1]
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.
Intergenic regions may contain a number of functional DNA sequences such as promoters and regulatory elements, enhancers, spacers, and (in eukaryotes) centromeres. [2] They may also contain origins of replication, scaffold attachment regions, and transposons and viruses.
Centromeres are well-associated with specific proteins that are involved in the formation of the kinetochore and the mitotic spindle. Because neocentromeres do not contain repetitive sequences, they are good candidates for studying the epigenetic regulation of distributing centromeric proteins, using chromatin immunoprecipitation (ChIP) methods.
This proteins is frequently accompanied by "centrochromatin"-associated changes to canonical histones and is constitutively present in centromeres. [8] The CENPA protein is a histone H3 variant which replaces one or both canonical H3 histones in a subset of nucleosomes within centromeric chromatin.