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In a molecular pathology report, the word rearrangement refers to a change in the DNA structure within a cell. DNA is usually organized into long strands called chromosomes, each containing many genes. A rearrangement happens when a piece of a chromosome breaks off and attaches somewhere else, either on the same chromosome or another chromosome.
- Table of Contents
- What Is Rearrangement reaction?
- Curtius Rearrangement Or Curtius Reaction
- Claisen Rearrangement
- Beckmann Rearrangement
- Hofmann Rearrangement
- Pericyclic Rearrangement
- Photochemical Rearrangements
On the other hand, a rearrangement may be a multi-step reaction that includes the migration of an H atom or of a larger molecular fragment as one of its steps. In many rearrangements, the migrating group connects to one of the direct neighbours of the atom to which it was originally attached. Rearrangements of this type are the so-called [1,2] – re...
Curtius’ reaction involves the heating of an acyl azide which loses nitrogen and then rearranges to an isocyanate. RCON3 → R-N=C=O + N2 If the reaction is performed in an alcoholic or aqueous medium, the isocyanate further reacts to form urethane, amine or substituted urea. The conversion of acyl azides to isocyanates involves Curtius rearrangement...
The classical Claisen rearrangement is the first and slow step of the isomerization of allyl aryl ethers to ortho allylated phenols. A cyclohexadienone is formed in the actual rearrangement step which is a [3,3]-sigmatropic rearrangement. Three valence electron pairs are shifted simultaneously. Cyclohexadienone, a non-aromatic compound, cannot be i...
In the Beckmann rearrangement , an oxime is converted to an amide . An oxime is easily obtained by treatment of aldehyde or ketone with hydroxylamine. The OH group of ketoximes can become a leaving group. The Beckmann rearrangement of cyclic oximes results in lactams. The comparison of the structure of the starting ketone with those of the products...
The Hofmann rearrangement results from the treatment of a primary amide with bromine and hydroxide ion in water, ultimately forming an amine in which the carbonyl group of the starting amide has been lost. Thus, the Hofmann rearrangement results in a shortening of the carbon chain by one atom and a change in functional group from an amide to an ami...
Pericyclic reactions are defined as the reactions that occur by a concerted cyclic shift of electrons. This definition states two key points that characterize a pericyclic reaction. 1. First point is that reaction is concerted. In concerted reaction, reactant bonds are broken and product bonds are formed at the same time without intermediates. 2. S...
Many photoreactions are known to interconvert isomeric compounds. The term “rearrangement” is more general than “isomerization” but for the reactions under photochemical rearrangement will not be concerned with a distinction between these terms. For convenience, we shall classify primary photochemical rearrangements as the following types. 1. Cis t...
DNA Rearrangements. Homologous recombination results in the reassortment of genes between chromosome pairs without altering the arrangement of genes within the genome. In contrast, other types of recombinational events lead to rearrangements of genomic DNA. Some of these DNA rearrangements are important in controlling gene expression in ...
- Geoffrey M Cooper
- 2000
Dec 30, 2022 · 16.9: DNA Rearrangement is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts. One of the central assumptions throughout our study of the cell has been that although the RNA and proteins in any cell may differ, any cell of a given organism other than the gametes should have the ….
REARRANGEMENT definition: 1. the act of changing the order, position, or time of arrangements already made: 2. the act of…. Learn more.
Gene Rearrangement. In subject area: Biochemistry, Genetics and Molecular Biology. Class switch recombination is the gene rearrangement process by which our B lymphocytes change from IgM production to IgG, IgA, or IgE. Unlike the well-characterized V (D)J recombination, the mechanism of class switch recombination has been largely enigmatic ...
Rearrangements can therefore influence the structure of the chromosome causing important effects on the phenotype and generating variability through the disruption of an existing gene, the creation of a new gene, or by changing the distance of a gene from the origin of chromosome replication (oriC), thereby modifying the number of copies of the gene and affecting its expression [24].
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