Ikke-kodende DNA: Forskelle mellem versioner

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...This parasite has implanted itself inside the cells of 70 percent of the world's invertebrates...
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Selvom det meste af junk-dna sekvenser formodes at være [[evolutionær]]e [[artefakt]]er, som ikke har noget aktuelt formål, tror nogle at junk-dna fungerer på måder, vi endnu ikke kender betydningen af.
<ref>[http://news.bbc.co.uk/2/hi/science/nature/6749213.stm 14 June 2007, BBC News: Human genome further unravelled] Citat: "...it suggests genes, so called junk DNA and other elements, together weave an intricate control network...He said: "The genome looks like it is far more of a network of RNA transcripts that are all collaborating together. Some go off and make proteins; [and] quite a few, although we know they are there, we really do not have a good understanding of what they do. "This leads to a much more complex picture." The researchers now hope to scale up their efforts to look at the other 99% of the genome..."</ref>
Ydermere kan bibeholdelsen af noget junk-dna over millioner af års evolution måske betyde, at de har en livsvigtig funktion. Nogle betragter mærkaten "junk" som en forkert benævnelse, mens andre anser junk-dna som dna gemt væk til mulig fremtidig anvendelse, i stedet for noget, der skal smides ud. Nogle foretrækker benævnelsen '''ikke-kodende dna''', selvom junk-dna ofte indeholder [[transposon]]er, der koder for [[protein]]er uden klar værdi for deres vært. Atter anden dna kommer fra parasitter. Et eksempel er f.eks. at 70% af [[hvirvelløse dyr]] har indlejret store dele eller næsten hele parasitten ''Wolbachia''s [[genom]] i deres genom.
<ref>[http://www.sciencedaily.com/releases/2007/08/070830150118.htm University of Rochester (2007, August 31). One Species' Entire Genome Discovered Inside Another's. ScienceDaily. Retrieved November 10, 2007] Citat: "..."This study establishes the widespread occurrence and high frequency of a process that we would have dismissed as science fiction until just a few years ago," says W. Ford Doolittle, Canada Research Chair in Comparative Microbial Genomics at Dalhousie University, who is not connected to the study. "This is stunning evidence for increased frequency of gene transfer."..."This parasite has implanted itself inside the cells of 70 percent of the world's invertebrates, coevolving with them. And now, we've found at least one species where the parasite's entire or nearly entire genome has been absorbed and integrated into the host's. The host's genes actually hold the coding information for a completely separate species."..."</ref>
 
[[Videnskab]]en [[funktionel genomik]] har udviklet mange accepterede teknikker til at karakterisere proteinkodende [[gen]]er, [[RNA-gen]]er og regulerende regioner. I det meste af [[plante]]s og [[dyr]]s genomer udgør det proteinkodende dna kun en mindre procentdel. I menneskets tilfælde mindre end 2 %. Funktionen af resten bliver undersøgt. Meget af det kan identificeres som repeterende dna-sekvenser uden kendt biologisk funktion for deres vært. Det er dog værdifuldt for [[genetiker]]e, da de kan anvende det til nedarvningsklassifikation. Men når dette er fratrukket junk-dna, er der stadig store mængder sekvenser, som indtil videre ikke kan klassificeres til andet end "junk".