Noncoding DNA, also known as "junk DNA" describes portions of the DNA sequence that do not appear to have any presentable use -- they do not encode for proteins, etc. In fact, in a most eukaryote cells, a rather large percentage of the total genome is noncoding DNA, but this varies between species. However, it is now a misnomer to call this material "junk," because the more sophisticated we become at biochemistry, we find that many do have subtle biological functions, including the transcriptional and translational regulation of certain protein-coding sequences. Researchers also belive that other noncoding sequences have a likely, but unconfirmed function, as an inference from high levels of inherited tratis and natural selection processes (Masters, 2005, 163-5).

Researchers know that the amount of genomic DNA varies widely between organisms, as does the proportion of coding and non-coding DNA within these genomes. For instance, 98% of the human...
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