Question by ms. murder: What region of a prokaryotic gene is analogous to the enhancer region of a eukaryotic gene?
1. What region of a prokaryotic gene is analogous to the enhancer region of a eukaryotic gene?
2. Describe how the intron-exon pattern of a gene organization can serve as a source of genetic diversity.
Yes, I know these are homework questions, but I really need help. You don’t have to answer them; explaining it would be greatly appreciated. Thank you.
Best answer:
Answer by gardengallivant
Prokaryotes have NtrC (nitrogen regulatory protein C) binding sites that act as enhancer-like DNA elements. The binding sites location at a distance from the promoter requires the prokaryote DNA to be looped or super coiled to bring them near the promoter so the NtrC protein can interact with RNA polymerase sigma 54 bound at the promoter site.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC556689/
http://genesdev.cshlp.org/content/12/6/894.long
Having exon sequences to be removed allows the option of alternative splicing so multiple proteins can be translated from one reading frame. These alternative proteins are regulated as to what cells they are expressed in and when in development. This regulated alternative protein expression is another inherited trait with allelic variations. The total range of allelic variation in a species is the base of its genetic diversity. A species with a large gene pool is more diverse than a species with a small gene pool. The gene pool is the number of alleles for each gene.
http://en.wikipedia.org/wiki/Alternative_splicing
Another aspect of exons is the idea some encode functional domains. If a functional domain is added to an existing gene a novel protein functional could result. The existence of isolated functional domains flanked by exon/intron splice sites facilitated this type of diversity at meiotic crossover. Crossover recombines homologous chromosomes and sometimes has additions. Crossover repairs the occasional addition/deletion to one chromosome by comparing to the partnered chromosome. This is how chromosomes rearrange over time.
http://bioinformatics.oxfordjournals.org/cgi/content/full/21/1/2
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