Gene expression

Gene expression, even for brief expression or expression referred to, in broad terms, how the genetic information - a gene ( segment of DNA ) - is expressed and its appearance is so like the genotype of an organism or cell pronounced than phenotype. In a narrow sense is the biosynthesis of proteins under expression (see protein ) fully understood from the genetic information necessary for it, together with all previous processes, starting with the synthesis of RNA transcription.

The difference in gene expression, for example, in (genetically identical) monozygotic twins a cause of slightly different phenotype; in genetically different individuals of the differences in phenotype based next to the modification mainly on differences in the genome.

Expiration

Which describes the synthesis of RNA transcription by the DNA template. In the subsequent RNA processing, RNA splicing are occasionally generated, provided with a cap structure and a poly -A tail. According to the base sequence of the mRNA in the RNA encoded amino acid sequence of a protein is produced in the course of the translation, after which changes in the last generated proteins carried in protein maturation, such as protein folding, protein splicing, autoproteolysis and posttranslational modifications.

The location of the gene on the chromosome ( the locus) determines its accessibility for these processes. The DNA is not linear inside the cell nucleus, but is folded (see Chromatin ); that is, a (gene ) section of DNA can be " hidden " by the fold so that it is not accessible for gene expression (eg, heterochromatin ). In addition, other proteins ( repressors and activators) attach to the key for the start of transcription and the actual gene upstream DNA segments (operators ) and thus reduce the rate of transcription or increase. By transcription factors, the activity of the gene can be amplified.

Gene expression can be determined by a gene expression analysis.

Regulation

More generally, regulation of gene expression take place at various levels. It can - especially in eukaryotes - the above principles interact with each other to form more complex regulatory mechanisms in the interaction between genetics and epigenetics.

Some genes are not subject to such regulation and are expressed independently of cell type, cell stage and growth conditions permanently evenly. These genes are constitutively expressed, including without limitation many housekeeping genes. The constitutive enzymes encoded by them keep the basic functions of a cell upright.

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