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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.
For example, an operon is a stretch of DNA that is transcribed to create a contiguous segment of RNA, but contains more than one cistron / gene. The operon is said to be polycistronic, whereas ordinary genes are said to be monocistronic.
Genetic regulatory circuits (also referred to as transcriptional regulatory circuits) is a concept that evolved from the Operon Model discovered by François Jacob and Jacques Monod. [ 1 ] [ 2 ] [ 3 ] They are functional clusters of genes that impact each other's expression through inducible transcription factors and cis-regulatory elements .
Regulation of the ccd operon by the CCdA/CCdB complex is dependent upon the ratio of the two molecules to each other in the complex: a (CcdA)2–(CcdB)2 complex binds the DNA of the operon thus repressing transcription, but when CcdB is in excess of CcdA de-repression occurs, whereas repression will occur when CcdA levels are greater than or ...
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.
An mRNA molecule is said to be monocistronic when it contains the genetic information to translate only a single protein chain (polypeptide). This is the case for most of the eukaryotic mRNAs. [27] [28] On the other hand, polycistronic mRNA carries several open reading frames (ORFs), each of which is
Chemical genetics is the investigation of the function of proteins and signal transduction pathways in cells by the screening of chemical libraries of small molecules. [1] Chemical genetics is analogous to classical genetic screen where random mutations are introduced in organisms, the phenotype of these mutants is observed, and finally the ...
(A) The vertical gene transfer of a toxin-antitoxin system. (B) Horizontal gene transfer of a toxin-antitoxin system. PSK stands for post-segregational killing and TA represents a locus encoding a toxin and an antitoxin. [1] A toxin-antitoxin system consists of a "toxin" and a corresponding "antitoxin", usually encoded by closely linked genes ...