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A typical operon. In genetics, an operon is a functioning unit of DNA containing a cluster of genes under the control of a single promoter. [1] The genes are transcribed together into an mRNA strand and either translated together in the cytoplasm, or undergo splicing to create monocistronic mRNAs that are translated separately, i.e. several strands of mRNA that each encode a single gene product.
The trp operon is a group of genes that are transcribed together, encoding the enzymes that produce the amino acid tryptophan in bacteria. The trp operon was first characterized in Escherichia coli , and it has since been discovered in many other bacteria. [ 1 ]
The lactose operon (lac operon) is an operon required for the transport and metabolism of lactose in E. coli and many other enteric bacteria.Although glucose is the preferred carbon source for most enteric bacteria, the lac operon allows for the effective digestion of lactose when glucose is not available through the activity of β-galactosidase. [1]
Regulation of gene expression by a hormone receptor Diagram showing at which stages in the DNA-mRNA-protein pathway expression can be controlled. Regulation of gene expression, or gene regulation, [1] includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products (protein or RNA).
Regulons involving virulence factors in pathogenic bacteria are of particular research interest; an often-studied example is the phosphate regulon in E. coli, which couples phosphate homeostasis to pathogenicity through a two-component system. [4] Regulons can sometimes be pathogenicity islands. [5]
The maltose operon is an example of a positive control of transcription. [1] When maltose is not present in E. coli, no transcription of the maltose genes will occur, and there is no maltose to bind to the maltose activator protein.
Jacques Monod and François Jacob used Escherichia coli, a type of bacteria, in order to develop the operon model of gene expression, which lay down the basis of gene expression and regulation. [54] Furthermore, the hereditary processes of single-celled eukaryotic microorganisms are similar to those in multi-cellular organisms allowing ...
Gene structure is the organisation of specialised sequence elements within a gene.Genes contain most of the information necessary for living cells to survive and reproduce. [1] [2] In most organisms, genes are made of DNA, where the particular DNA sequence determines the function of the gene.