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Cis-regulatory DNA sequences that are located in DNA regions distant from the promoters of genes can have very large effects on gene expression, with some genes undergoing up to 100-fold increased expression due to such a cis-regulatory sequence. [3] These cis-regulatory sequences include enhancers, silencers, insulators and tethering elements. [4]
The human genome has many different regulatory sequences which are crucial to controlling gene expression. Conservative estimates indicate that these sequences make up 8% of the genome, [27] however extrapolations from the ENCODE project give that 20 [28] or more [29] of the genome is gene regulatory sequence.
Linkage disequilibrium has identified more than 30,000 hotspots within the human genome. [3] In humans, the average number of crossover recombination events per hotspot is one crossover per 1,300 meioses, and the most extreme hotspot has a crossover frequency of one per 110 meioses. [4]
These are prevalent motifs within 3'-UTRs. Among all regulatory motifs within the 3'-UTRs (e.g. including silencer regions), MREs make up about half of the motifs. As of 2014, the miRBase web site, [29] an archive of miRNA sequences and annotations, listed 28,645 entries in 233 biologic species. Of these, 1,881 miRNAs were in annotated human ...
Whereas one could think that there is a 1:1 enhancer-promoter ratio, studies of the human genome predict that an active promoter interacts with 4 to 5 enhancers. Similarly, enhancers can regulate more than one gene without linkage restriction and are said to “skip” neighboring genes to regulate more distant ones.
Gene order is the permutation of genome arrangement. A fair amount of research has been done trying to determine whether gene orders evolve according to a molecular clock ( molecular clock hypothesis ) or in jumps ( punctuated equilibrium ).
Schematic karyogram of a human, showing an overview of the expression of the human genome using G banding, which is a method that includes Giemsa staining, wherein the lighter staining regions are generally more transcriptionally active, whereas darker regions are more inactive.
March 2001 – National Human Genome Research Institute (NHGRI) and Human Genome Project (HGP)-funded scientists find a new tumor suppressor gene involved in breast, prostate and other cancers on human chromosome 7. A single post-doc, using the "working draft" sequence data, is able to pin down the gene within weeks; before, the same work took ...