Is there 3/4 "garbage" in our DNA?
The human genome is 75% made up of junk DNA
Alexander Khramov, Infox.ru
Scientists have stated that only a quarter of the human genome is functional. Everything else relates to junk DNA, mutations in which do not affect survival in any way, reports Infox.
This was stated by only one scientist. Here is his portrait from the press release
New Limits to Functional Portion of Human Genome Reported – VM :)
This is stated in an article by American geneticist Dan Grauer from the University of Houston, published in the journal Genome Biology and Evolution: Dan Graur, An upper limit on the functional fraction of the human genome.
Junk DNA refers to sections of the genome in which information about proteins or RNA molecules is not encoded. For a long time it was believed that up to 99% of the human genome belongs to such non-coding sequences. However, in 2012, ENCODE project participants stated that about 80% of junk DNA sites are actually functional and play an important role in regulating gene activity.
Grauer questioned this conclusion based on the rate of accumulation of harmful mutations. In humans, 1-2.5 mutations per 100 million nucleotide bases ("letters" of DNA) occur in one generation. If mutations occur in junk DNA, then they have no effect on the body. If mutations occur in coding sequences, then 40% of them fall into the category of harmful ones – they negatively affect health, or even lead to the death of a person before he managed to reproduce.
To compensate for the natural decline of offspring due to harmful mutations, on average, each couple should give birth to more than two children. For most of the history of mankind, this figure was 2.1-3.5 children. According to Gruer, such a level of fertility suggests that harmful mutations do not occur very often, since a significant part of mutations occur in junk DNA and, therefore, it occupies most of the genome.
According to Grauer's calculations, no more than 25% of our entire genome is functional and, therefore, susceptible to harmful mutations. Otherwise, people would have to reproduce much faster in order not to die out due to congenital pathologies. For example, if 80% of the human genome carried some kind of function, as the participants of the ENCODE project claim, then couples would have to give birth to 15 children so that mutations would not bring the human race to naught.
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18.07.2017