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Simple and concise definition: Chromatin is a macromolecular complex of a DNA macromolecule and protein macromolecules (and RNA). The proteins package and arrange the DNA and control its functions within the cell nucleus. A biochemists' operational definition: Chromatin is the DNA/protein/RNA complex extracted from eukaryotic lysed interphase ...
Chromatin contains the vast majority of the DNA in an organism, but a small amount inherited maternally can be found in the mitochondria. It is present in most cells, with a few exceptions, for example, red blood cells. Histones are responsible for the first and most basic unit of chromosome organization, the nucleosome.
Diagram of the nucleus showing the ribosome-studded outer nuclear membrane, nuclear pores, DNA (complexed as chromatin), and the nucleolus. The nucleus contains nearly all of the cell's DNA, surrounded by a network of fibrous intermediate filaments called the nuclear matrix, and is enveloped in a double membrane called the nuclear envelope.
Chromatin refers to the combination of DNA and proteins that make up chromosomes. When a cell is not dividing, chromosomes exist as loosely packed chromatin mesh. [3] The genome of an organism (encoded by the genomic DNA) is the (biological) information of heredity which is passed from one generation of organism to the next.
Silica glass is another example of a material which is organized into a paracrystalline lattice. A paracrystalline lattice, or paracrystal, is a molecular or atomic lattice with significant amounts (e.g., larger than a few percent) of partial disordering of molecular arrangements.
In the diagram, (1) refers to a chromatid: 1-half of two identical threadlike strands of a replicated chromosome. During cell division, the identical copies (called a " sister chromatid pair ") are joined at the region called the centromere (2).
The bacterial DNA is not packaged using histones to form chromatin as in eukaryotes but instead exists as a highly compact supercoiled structure, the precise nature of which remains unclear. [6] Most bacterial chromosomes are circular, although some examples of linear chromosomes exist (e.g. Borrelia burgdorferi). Usually, a single bacterial ...
The loop structures extending from chromomeres are maintained by a high level of transcriptional activity and structural proteins of the chromosome. Chromatin within the chromomere are held in position by a variety of histone modifications and epigenetic markers. [5] Methyl-CpG-binding protein 2 (MeCP2) is a protein that binds to methylated DNA ...