Added: Larenzo Dorado - Date: 17.09.2021 07:36 - Views: 29635 - Clicks: 7023
By Michael Le. The code that makes us is at least 75 per cent rubbish, according to a study that suggests most of our DNA really is junk after all.
After 20 years of biologists arguing that most of the human genome must have some kind of function, the study calculated that in fact the vast majority of our DNA has to be useless. But we each have just a few children on average, and our genetic health is mostly fine. The study therefore concludes that most of our DNA really must be junk — a suggestion that contradicts controversial claims to the contrary from useless junk group of prominent genomics researchers in When researchers first worked out how DNA encodes the instructions for making proteins in the s, they assumed that almost all DNA codes for proteins.
However, by the s, it was becoming clear that only a tiny proportion of a genome encodes functional proteins — about 1 per cent in the case of us humans. Biologists realised that some of the non-coding DNA might still have an important role, such as regulating the activity of the protein-coding genes.
But around 90 per cent of our genome is still junk DNA, they suggested — a term that first appeared in print in a article in New Scientist. But throughout the s, a of studies purported to show that junk DNA was nothing of the sortbased on useless junk that some tiny bits of non-coding DNA had some use or other.
These claims proved popular with creationists, who were struggling to explain why an intelligently deed genome would consist mostly of rubbish. The grandest claim came inwhen a consortium of genomics researchers called ENCODE declared that, according to their project, a huge 80 per cent of the DNA in the human genome has a function. The heart of the issue is how you define functional.
Instead, he argues that a sequence can only be described as functional if it has evolved to do something useful, and if a mutation disrupting it would have a harmful effect. These mutations change one base of DNA into another — an A to a T, for example — and when they occur in a gene are more likely to be harmful than beneficial. Useless junk we reproduce, our children inherit a shuffled bag of mutations, and those with a collection of particularly bad ones are more likely to die before having children of their own.
This is how evolution stops bad mutations building up to dangerously high levels in a species. But if most of our DNA is junk, the majority of mutations would have no effect. If the entire genome was functional, couples would need to have around million children, and almost all would have to die.
Even if just a quarter of the genome is functional, each couple would still have to have nearly four children on average, with only two surviving to adulthood, to prevent harmful mutations building up to dangerous levels. This ties in nicely with a study that compared our genome with other species and concluded that around 8 per cent of it is functional. But even taking this intomost DNA is probably junk, says Gregory.
The challenge for those who think most non-coding DNA is vital is to explain why an onion needs five times as much of it as we dosays Gregory. But most people and even some scientists are uncomfortable with the idea that most of their DNA is junk, says Ponting. Even worse for such people, other genomic studies are now revealing that we all carry plenty of mutations that affect both our coding DNA and non-coding DNA. Trending Latest Video Free. The eternal debate about the eternal inflation of the universe Useless junk will ignore you if they know you are lying, unlike young children Why chemical pollution is turning into a third great planetary crisis We have just two years to stop deep-sea mining from going ahead How is gold made?
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