A sheet it is an iron or a very thin object, the surface of which is greater than its thickness. It is possible to find sheets of various materials, such as metal, paperboard or paper. For instance: “I have to bring a sheet with pictures of the family to school”, “We need several aluminum sheets to finish building the shed”, “The cake had, on the top, a thin sheet of chocolate”.
In the field of engineering and of the building, the sheet is a structural element made of a deformable solid, allowing you to work at flexion. They differ from plates in that they are flat, while plates are curved in three-dimensional space.
A sheet, in another sense, is a He drew or one stamp that is obtained through engraving. By extension, the total figure of a person or an animal. The plates, in this case, are frequent in school.
For the geology, a sheet or mantle is a tabular mass of igneous rock that is located parallel to the rock strata of the area. The botanyInstead, it uses the notion of lamina to refer to the widest part of the leaves and petals.
The structure found under the hat of a mushroom; the set of networks that provide mechanical support to the nucleus of a cell; a portion of proteins; a group of musical instruments; and the thin, flat part of the bones, the membranes, the tissues and cartilage of organic beings are also called sheet.
It is known by the name of nuclear lamina to a net intermixed of intermediate filaments, with a thickness ranging from 15 to 80 nm and which are composed of sheets A, B and C found around the nuclear hyaloplasm (semi-liquid internal environment of the cell nucleus, where chromatin and nucleoli are submerged). Laminates are the proteins on which the composition of the nuclear lamina is based.
The nuclear envelope benefits from the stability provided by the lamina, which also intervenes in the three-dimensional organization of the nucleus at rest (also called interphase, is the structure that the nucleus presents while the cell does not divide), through its interaction with chromatin.
Each type of sheet (A, B and C, as mentioned in the first paragraph) presents a coding by three genes different. The synthesis of type A and C takes place starting from the same gene, called LMNA; It is given by alternative processing and four subtypes emerge from this, which are A, A (Δ) 10, C1 and C2. Those of type B, on the other hand, are encoded by two genes: LMNB1 and LMNB2, lamins of subtype B1 and subtypes B2 and B3, respectively.
In all cases, the plates show a domain globular at the N-terminus and at the C-terminus; by means of the latter, those of type A and B unite a molecule named farnesyl which makes it possible to anchor the laminae to the inner nuclear membrane. Thanks to this bond, dimers can be formed and, later, tetramers, protofilaments, filaments and, finally, the reticulum of the nuclear lamina itself.
The diseases rare forms of the nuclear lamina that have in common wrong forms of genetic coding of the laminae are called laminopathies. These are disorders that involve various functions and tissues, such as striated muscle, bone, adipose, and the nervous system. Some of the best known laminopathies are Hutchinson-Gildford Progeria syndrome and Emery-Dreifuss muscular dystrophy.