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The largest regions on each chromosome are the short arm p and the long arm q, separated by a narrow region near the center called the centromere. [1] Other specific regions have also been defined, some of which are similarly found on every chromosome, while others are only present in certain chromosomes. Named regions include: Arms (p and q ...
Chromosome replication proceeds in three major stages: initiation, elongation and termination. The initiation stage starts with the ordered assembly of "initiator" proteins at the origin region of the chromosome, called oriC. These assembly stages are regulated to ensure that chromosome replication occurs only once in each cell cycle.
The 23 human chromosome territories during prometaphase in fibroblast cells In cell biology , chromosome territories are regions of the nucleus preferentially occupied by particular chromosomes . Interphase chromosomes are long DNA strands that are extensively folded, and are often described as appearing like a bowl of spaghetti .
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]
Some sequences are required for a properly functioning chromosome: Centromere: Used during cell division as the attachment point for the spindle fibers. Telomere: Used to maintain chromosomal integrity by capping off the ends of the linear chromosomes. This region is a microsatellite, but its function is more specific than a simple tandem repeat.
These regions often correspond to promoter regions of genes that were active in that cell type prior to chromatin formation. The lack of compaction of these regions is called bookmarking , which is an epigenetic mechanism believed to be important for transmitting to daughter cells the "memory" of which genes were active prior to entry into ...
But this is only present when the cell divides. Researchers have now been able to model the structure of chromosomes when they are active. This is extremely important because the way that DNA folds up in chromosome structures is linked to the way DNA is used. Scientists have been able to develop the 3D structures of chromosomes in a single cell.
In biology, the chromosome scaffold is the backbone that supports the structure of the chromosomes. It is composed of a group of non-histone proteins that are essential in the structure and maintenance of eukaryotic chromosomes throughout the cell cycle. These scaffold proteins are responsible for the condensation of chromatin during mitosis. [1]