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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.
Three of these genes are found upstream while the other three genes are found downstream of the trp operon. [16] There is a 7th gene in Bacillus subtilis's operon called trpG or pabA which is responsible for protein synthesis of tryptophan and folate. [17] Regulation of trp operons in both organisms depends on the amount of trp present in the cell.
Most bacterial cells including E. coli lack introns in their genome. They also lack a nuclear membrane. Hence the gene regulation by lac operon occurs at the transcriptional level, by preventing conversion of DNA into mRNA. Bacterial operons are polycistronic transcripts that are able to produce multiple proteins from one mRNA transcript.
In fact, many prokaryotic genes occur in operons, which are a series of genes that work together to code for the same protein or gene product and are controlled by a single promoter. [2] Bacterial RNA polymerase is made up of four subunits and when a fifth subunit attaches, called the sigma factor (σ-factor), the polymerase can recognize ...
The Ada regulon in E. coli is a well-characterized example of a group of genes involved in the adaptive response form of DNA repair. [6] Quorum sensing behavior in bacteria is a commonly cited example of a modulon or stimulon, [7] though some sources describe this type of intercellular auto-induction as a separate form of regulation. [1]
Transfer genes or tra genes (also transfer operons or tra operons), are some genes necessary for non-sexual transfer of genetic material in both gram-positive and gram-negative bacteria. The tra locus includes the pilin gene and regulatory genes, which together form pili on the cell surface, polymeric proteins that can attach themselves to the ...
The L-arabinose operon, also called the ara or araBAD operon, is an operon required for the breakdown of the five-carbon sugar L-arabinose in Escherichia coli. [1] The L-arabinose operon contains three structural genes: araB, araA, araD (collectively known as araBAD), which encode for three metabolic enzymes that are required for the metabolism of L-arabinose. [2]
In molecular biology, the ars operon is an operon found in several bacterial taxon. It is required for the detoxification of arsenate, arsenite, and antimonite. [1] This system transports arsenite and antimonite out of the cell. The pump is composed of two polypeptides, the products of the arsA and arsB genes.