Junk DNA?
DNA. Everyone should know how important DNA is. DNA, its so small, yet it is so complex and so important. It is essentially the manuscript to your life. However, what if I told you that there was a significant portion of your DNA that was junk? Pointless? Absolutely unnecessary?
Hopefully, some of y'all would say that is a little extreme, but not that long ago, this is what most scientists thought.
So, let me elaborate. The "junk DNA" that I am referring to is the portion of DNA that does not code for proteins, otherwise called non-coding DNA. Now, non-coding DNA doesn't sound half as bad as junk DNA, but this term was formally coined in 1972 by Susumo Ohno. Although, Ohno coined the term, David Comings was the first to discuss the nature of junk DNA and this idea became really popular in the 60s. It was found that of the 20,000 genes that humans have, only 1.2 percent of these genes actually code. The remaining 98.8 percent are noncoding genes.
Non-coding DNA is still very valuable. Non-coding DNA can be used to produce non-coding RNA components such as transfer RNA, regulatory RNA and ribosomal RNA. Other non-coding DNA regions uses are actually unknown. There are many hypotheses as to what these extra areas do, but no one is actually sure.
These non-coding genes also contribute to something that is called the C-Value Paradox. Humans are considered really complex organisms, and the number of base pairs in our DNA sits at about 3.2 billion base pairs. However, an Amoeba, one of the most simplest organisms out there has 670 billion base pairs! Its insane to think that something so small and simple would have so many base pairs, but then again the majority are non-coding.
This may have some kind of evolutionary reasoning behind so many non-coding genes, or it could be a sort of housekeeping mechanism. The uncertainty is still there as to why we have so many non-coding genes, but I can say that they are most definitely not junk.
The term "junk DNA" has been slowly replaced by non-coding DNA because scientists simply don't like calling DNA junk. Maybe one day, we can recognize every gene function, if they have one. Maybe they really are useless.
Hopefully, some of y'all would say that is a little extreme, but not that long ago, this is what most scientists thought.
So, let me elaborate. The "junk DNA" that I am referring to is the portion of DNA that does not code for proteins, otherwise called non-coding DNA. Now, non-coding DNA doesn't sound half as bad as junk DNA, but this term was formally coined in 1972 by Susumo Ohno. Although, Ohno coined the term, David Comings was the first to discuss the nature of junk DNA and this idea became really popular in the 60s. It was found that of the 20,000 genes that humans have, only 1.2 percent of these genes actually code. The remaining 98.8 percent are noncoding genes.
Non-coding DNA is still very valuable. Non-coding DNA can be used to produce non-coding RNA components such as transfer RNA, regulatory RNA and ribosomal RNA. Other non-coding DNA regions uses are actually unknown. There are many hypotheses as to what these extra areas do, but no one is actually sure.
These non-coding genes also contribute to something that is called the C-Value Paradox. Humans are considered really complex organisms, and the number of base pairs in our DNA sits at about 3.2 billion base pairs. However, an Amoeba, one of the most simplest organisms out there has 670 billion base pairs! Its insane to think that something so small and simple would have so many base pairs, but then again the majority are non-coding.
This may have some kind of evolutionary reasoning behind so many non-coding genes, or it could be a sort of housekeeping mechanism. The uncertainty is still there as to why we have so many non-coding genes, but I can say that they are most definitely not junk.
The term "junk DNA" has been slowly replaced by non-coding DNA because scientists simply don't like calling DNA junk. Maybe one day, we can recognize every gene function, if they have one. Maybe they really are useless.
When I first herd of Junk DNA my first thought was maybe we don't know what it does yet. Our DNA seems to have more details than we at first thought to consider. Like you said we now know some if it is for noncoding RNA. Possibly the length of it must have a minimum in order for certain replication methods to occur or certain codes are needed for normal functioning. Some I think may be left over from ancestry. Also I think about Histones and their function which is to wrap DNA. The DNA which is near Histones are not as easily used for producing function to a cell. This area is more likely to be junk DNA than other parts, but even these could at one point in the future or our history have served a purpose.
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