Within a chromosome or a genome, the junk DNA is those portions of the DNA for which no function has been identified. About 98.5% of the human genome has been designated as "junk", including most sequences within introns and most intergenic DNA. While much of this sequence is probably an an evolutionary artifact that serves no present-day purpose, some may function in ways that are not currently understood. Among some of the hypothesis that supports junk DNA is listed below:
- Junk DNA may have no function. For example, recent experiments removed 1% of the mouse genome and were unable to detect any effect on the phenotype. This result suggests that the DNA is, in fact, non-functional. However, it remains a possibility that there is some function that the experiments performed on the mice were merely insufficient to detect.
- Junk DNA may act as a protective buffer against genetic damage and harmful mutations. For example, a high proportion of nonfunctional sequence makes it unlikely that a functional element will be destroyed in a Chromosal recover event, possibly making a species more tolerant to this important mechanism of genetic recombination.
- Junk DNA may serve other, unknown purposes.
- Some portions of junk DNA could serve presently unknown regulatory functions, controlling the expression of certain genes and/or the development of an organism from embryo to adult.
Ive got my own idea on these Junk DNA issue, that i will share it over here:
It is common knowledge that we only use bout 10% of our brain and the other 9-% is not used. we are only constructed from about 3% of our DNA and the other 97% is called junk DNa. why they call it as junk is because they believed it was actually a leftover DNA from our evolution. The real truth is that IT IS OUR FUTURE!! I is not our past at all. It is our new ability and potential to design our future as a new species. It will be as radical as when human beings moved from being Homo erectus to Homo sapiens. It is when we moved from living out of our nervous system, our parasympathetic and our sympathetic fight system of survival of the fittest, to becoming the thinking human. It is when we moved into consciousness......