Search results
Results from the WOW.Com Content Network
The nucleosome is the fundamental subunit of chromatin. Each nucleosome is composed of a little less than two turns of DNA wrapped around a set of eight proteins called histones, which are known as a histone octamer. Each histone octamer is composed of two copies each of the histone proteins H2A, H2B, H3, and H4.
Histones are responsible for maintaining the shape and structure of a nucleosome. One chromatin molecule is composed of at least one of each core histones per 100 base pairs of DNA. [2] There are five families of histones known to date; these histones are termed H1/H5, H2A, H2B, H3, and H4. [3]
The nucleosome assembles when DNA wraps around the histone octamer, two H2A-H2B dimers bound to an H3-H4 tetramer. The nucleosome core particle is the most basic form of DNA compaction in eukaryotes. Nucleosomes consist of a histone octamer surrounded by 146 base pairs of DNA wrapped in a superhelical manner. [10]
In molecular biology, linker DNA is double-stranded DNA (38-53 base pairs long) in between two nucleosome cores that, in association with histone H1, holds the cores together. Linker DNA is seen as the string in the "beads and string model", which is made by using an ionic solution on the chromatin. Linker DNA connects to histone H1 and histone ...
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]
In eukaryotic cells, DNA is associated with about an equal mass of histone proteins in a highly condensed nucleoprotein complex called chromatin. [14] Deoxyribonucleoproteins in this kind of complex interact to generate a multiprotein regulatory complex in which the intervening DNA is looped or wound.
The small intestine is the site where most of the nutrients from ingested food are absorbed. The inner wall, or mucosa, of the small intestine, is lined with intestinal epithelium, a simple columnar epithelium. Structurally, the mucosa is covered in wrinkles or flaps called circular folds, which are considered permanent features in the mucosa.
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 ...