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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]
Location of eukaryote nuclear DNA within the chromosomes. DNA usually occurs as linear chromosomes in eukaryotes, and circular chromosomes in prokaryotes. The set of chromosomes in a cell makes up its genome; the human genome has approximately 3 billion base pairs of DNA arranged into 46 chromosomes. [96]
This represents the size of a composite genome based on data from multiple individuals but it is a good indication of the typical amount of DNA in a haploid set of chromosomes because the Y chromosome is quite small. [7] Most human cells are diploid so they contain twice as much DNA (~6.2 billion base pairs).
In eukaryotes, such as humans, roughly 3.2 billion nucleotides are spread out over 23 different chromosomes (males have both an X chromosome and a Y chromosome instead of a pair of X chromosomes as seen in females). Each chromosome consists enormously long linear DNA molecule associated with proteins that fold and pack the fine thread of DNA ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 22 February 2025. DNA molecule containing genetic material of a cell This article is about the DNA molecule. For the genetic algorithm, see Chromosome (genetic algorithm). Chromosome (10 7 - 10 10 bp) DNA Gene (10 3 - 10 6 bp) Function A chromosome and its packaged long strand of DNA unraveled. The DNA's ...
In nature, DNA can form three structures, A-, B-, and Z-DNA. A- and B-DNA are very similar, forming right-handed helices, whereas Z-DNA is a left-handed helix with a zig-zag phosphate backbone. Z-DNA is thought to play a specific role in chromatin structure and transcription because of the properties of the junction between B- and Z-DNA.
The vast expansion of the genome with noncoding and repetitive DNA in higher eukaryotes implies more extensive epigenetic silencing mechanisms. Studies of the genomic organization are thought to be the future of genomic medicine, which will provide the opportunity for personalized prognoses in clinics. [4]
DNA quaternary structure is used to refer to the binding of DNA to histones to form nucleosomes, and then their organisation into higher-order chromatin fibres. [2] The quaternary structure of DNA strongly affects how accessible the DNA sequence is to the transcription machinery for expression of genes. DNA quaternary structure varies over time ...