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The words cistron and gene were coined before the advancing state of biology made it clear to many people that the concepts they refer to, at least in some senses of the word gene, are either equivalent or nearly so. The same historical naming practices are responsible for many of the synonyms in the life sciences.
The primary RNA transcript of a gene is cleaved at the poly-A addition site, and 100–200 A's are added to the 3' end of the RNA. If this site is altered, an abnormally long and unstable mRNA construct will be formed.
Multicistronic message is an archaic term for Polycistronic. Monocistronic, bicistronic and tricistronic are also used to describe mRNA with single, double and triple coding areas (exons). Note that the base word cistron is no longer used in genetics, and has been replaced by intron and exon in eukaryotic mRNA. However, the mRNA found in ...
IRES sequences are often used in molecular biology to co-express multiple genes under the control of the same promoter, thereby mimicking a polycistronic mRNA. Within the past decades, IRES sequences have been used to develop hundreds of genetically modified rodent animal models. [ 12 ]
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.
A simple gene prediction algorithm for prokaryotes might look for a start codon followed by an open reading frame that is long enough to encode a typical protein, where the codon usage of that region matches the frequency characteristic for the given organism's coding regions. [5]
Thus, many viruses (including HIV-1) are categorized as having a polycistronic genome, meaning they employ multiple active ORF's in a single gene. [ 2 ] The HIV-1 virus requires a programmed -1 ribosomal frameshift signal (the HIV-1 Ribosomal Frameshift Signal) for the expression of the Pol gene, which is an example of a cis-acting element of ...
Trans-splicing is a special form of RNA processing where exons from two different primary RNA transcripts are joined end to end and ligated.It is usually found in eukaryotes and mediated by the spliceosome, although some bacteria and archaea also have "half-genes" for tRNAs.