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Every gene can have a tag attached to it which prevents the gene from being used to create RNA (the tag is a methyl group, so this is called "methylation"). Sin
by db48x 9y ago
Every gene can have a tag attached to it which prevents the gene from being used to create RNA (the tag is a methyl group, so this is called "methylation"). Since the RNA would then be used as instructions for creating a protein molecule, inactivating a gene by tagging it generally causes the cell to stop producing particular proteins. Since each protein has one or more specific jobs to do in the cell, this causes the behavior of the cell to change. There are a huge number of known proteins (millions maybe? I don't actually know), and a vast potential number of proteins (if you just consider all possible ways of arranging the 20 amino acids into a chain), so there are a vast number of ways that cell behavior can change over time. Indeed, this is how we manage to have different types of tissues at all, including our very complicated immune system with cells that act autonomously to protect against disease.
Also, it's well established that there are plenty of feedback loops here. An active gene can code for the production of a protein that activates or inactivates other genes. There are numerous pathways by which external stimuli can amplify or inhibit all of these feedback loops, so external conditions often result in changes to which genes are tagged.
As you can imagine, the state-space of all of this is immense; far larger than just the number and type of genes that you have. Mapping it all is a vast project that might easily take thousands of years.
- ggoss 9y agoThe well goes deeper still. Another mode of epigenetic regulation involves histones, the proteins around which DNA is wrapped, and the many ways they can be modified (by methylation, acetylation, ubiquitiylation, sumoylation, etc.). Both DNA methylation and histone modifications modulate how DNA wraps around histones, and thus how readily any given segment can be accessed and transcribed into RNA (and eventually translated into a given protein). This barely scratches the surface. This process, along with others that modify how DNA is folded, brings certain genes closer together (while moving others farther apart), increasing (or decreasing) the likelihood of all sorts of first, second, and third order (...) interactions between them and their products. And we've only just begun...
- psychobabble 9y ago> This well goes deeper still > This barely scratches the surface. This process, along with others that modify how DNA is folded, brings certain genes closer together (while moving others farther apart), increasing (or decreasing) the likelihood of all sorts of first, second, and third order (...) interactions between them and their products. > And we've only just begun... Horribly vague, care to elaborate mathematically or at least provide some study links? The 'DNA folding' you propose begs resolution from some study using quaternions or attractors, or ... ?
- Sharlin 9y agoI see your username is accurate.
- Chris_Jay 9y agoEpigenetics are fascinating. In my D&D headcanon, the reason Drow Elves are so obsessed with spiders is because they picture DNA as a three dimensional web whose spatial arrangement is central to gene expression.
- fnl 9y agoThis view that epigenetics is a gene switch is actually pretty misleading at least, and probably just plain wrong, as recent research published this year has shown. It is far more a structural and inheritance guiding factor, as it was conclusively shown that methylated promoters very much do still allow for gene expression, contrary to "popular" belief.
- db48x 9y agoThat doesn't surprise me in the least; practically everything in biology has turned out to be more complicated than it first looked.