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The Gene Is Having an Identity Crisis
gollum123 writes "New large-scale studies of DNA are causing a rethinking of the very nature of genes. A typical gene is no longer conceived of as a single chunk of DNA encoding a single protein. It turns out, for example, that several different proteins may be produced from a single stretch of DNA. Most of the molecules produced from DNA may not even be proteins, but rather RNA. The familiar double helix of DNA no longer has a monopoly on heredity: other molecules clinging to DNA can produce striking differences between two organisms with the same genes — and those molecules can be inherited along with DNA. Scientists have been working on exploring the 98% of the genome not identified as the protein-coding region. One of the biggest of these projects is an effort called the Encyclopedia of DNA Elements, or 'Encode.' And its analysis of only 1% of the genome reveals the genome to be full of genes that are deeply weird, at least by the traditional standard of what a gene is supposed to be and do. The Encode team estimates that the average protein-coding region produces 5.7 different transcripts. Different kinds of cells appear to produce different transcripts from the same gene. And it gets even weirder. Our DNA is studded with millions of proteins and other molecules, which determine which genes can produce transcripts and which cannot. New cells inherit those molecules along with DNA. In other words, heredity can flow through a second channel."
A thread on DNA and its relationship to RNA gives me a chance to ask: what ever happened to the idea that memory was encoded in RNA? In 1970s science fiction novels like Niven's A World out ot Time , you had people learning new skills through the injection of RNA. When did it become clear that RNA had nothing to do with memory?
This from the people who claimed that most of the DNA in our cells was just junk. I wonder why they were so bloody arrogant? Couldn't they just have acknowledged that they had no clue?
Don't take my word for it, take the word of a cellular biologist.
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I recall people freaking out when the human genome project revealed that Humans only have about 30,000 genes rather than the previous estimate of 150K.
It always seemed to me that measuring Human complexity based on the number of our genes is a little like judging a book by the number of words it contains. It completely ignores the fact that words have Meaning.
Poetry is both the most compact and the most subtle form of written expression.
This latest finding suggests to me that something similar applies to our genetic heritage.
-S
Does anyone else see the resemblence between DNA and crufted up old legacy software? Concepts about how heredity works get turned on their head once the mechanisms are examined in detail. I expect next it will be discovered that there are bugs in the DNA transcoding that are fixed by patches which in turn have patches.
If you post it, they will read.
I recall people freaking out when the human genome project revealed that Humans only have about 30,000 genes rather than the previous estimate of 150K.
It always seemed to me that measuring Human complexity based on the number of our genes is a little like judging a book by the number of words it contains. It completely ignores the fact that words have Meaning.
Uh, I remember when they discovered that too, and I don't recall any scientists "freaking out" because the low number of genes implied we had low "complexity". Instead, I remember them being very excited, because they already knew there are far more than 30,000 proteins generated from our DNA, meaning that the 1:1 gene:protein mapping theory had to be wrong, and the mechanism was far more complicated than previously thought.
This sounds to me like a continuation of the line of inquiry opened by that discovery years ago, where now they're gaining a better idea of how the genes really code for proteins. With the extremely interesting aspect that some of this is controlled by things not part of the DNA itself, yet which can still be inherited.
To (ab)use your analogy, if the human body is a work of literature then proteins are the words, and genes are characters. The number of words hasn't changed, it's just that before we thought the language was like Chinese, where a single character mapped to a single word. Now we realize it's more like English, where the interactions between characters create different words. Oh and now we've discovered that there's also punctuation like apostrophes and hyphens which can significantly alter the meaning of the resulting words.
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The debate was philosophical at the heart of it, because at the root of the debate was the problem of nature vs nurture. Many happy about the discovery were using it ease their fear that human behavior could be traced to genes.
Some of it is new, but none of it is surprising to anyone who has been paying attention for, I dunno, the past decade.
It's been clear since the mid-90's when we learned that there were only 44k "coding" genes but at least ten times that many proteins that more was going on than simple templating.
Things like methylation of double-stranded DNA have been known to be important in oncogenesis for at least ten years. miRNAs have been considered important for five years or more. Other conserved non-coding regions have been known for almost as long or longer.
This story is going to be like that "green" story that reports breathlessly every year or so that some company has instituted green policies because they save money! Just like Interface did fifteen years ago, and hundreds of others have done since.
The interesting thing is that these persistently "new" stories give us a measure of how slowly what can fairly be called "general knowledge" changes. Based on evidence from the "green" story we can expect to be hearing the AMAZING NEWS that there's more to genes than template coding until at least 2020.
Following the details as we learn them is fascinating. Being told that an uncontroversial fact we've known for a decade or more is "news" is very, very irritating.
Blasphemy is a human right. Blasphemophobia kills.
There is a theory that states that whenever anybody discovers exactly what The Universe is and what it should be called, it will instantly disappear and be replaced with something even more bizarrely inexplicable. There is another theory that states that this has already happened.