This is the definition of epigenome I found – ‘The epigenome is made up of chemical compounds and proteins that can attach to DNA and direct such actions as turning genes on or off’
What is responsible for creating the chemical compounds and proteins that are apart of the epigenome?
I remember proteins are created from the DNA.
In: Biology
The epigenome is more abstract than that, it’s the whole modification of genome in a way that doesn’t alter the actual sequence. This is basically a way to affect the expression of a gene either by directly modifying the DNA sequence covalently or by modifying the histones covalently. Such covalent modifications include methylation, hydroxymethylation, acetylation, phosphorylation, ubiquitination and sumoylation. Enzymes like DNA methyltransferase and histone deacetylase catalyze such reactions like any other enzyme, they use a commonly present substrate in the cell and chemically modify and add it. The chemical moieties are not special, they’re used for many many things, theyre just small proteins (and chemical groups) added covalently to the DNA bases or the amino acids making up histones. Not all of these apply to both DNA and histones, some to both some to one or the other. And of course there are sooooo many other things in epigenetic regarding many types of RNA and such, but let’s not get too complex. Btw, histones are proteins that the DNA wraps around in many layers of organization to condense it (since it’s extremely long), and when you transcribe a gene you usually loosen this binding a bit to make it accessible, so if you modify those histones you may either reduce or enhance the tightness of the wrapping, thereby affecting gene expression. For methylation (as a common example), when it happens on DNA it is thought to recruit some proteins that repress gene expression or it directly inhibits the binding of transcription factors. When it’s on histones, it functions to wrap the tail of the histones tighter around the DNA to restrict access of transcription factors that can facilitate the expression of the gene. And methylation is not permanent, it can be written and erased, but it does play a role in genomic imprinting where your parent can transmit their DNA methylation to their offspring, that’s how x chromsome silencing works (women have two and one is silenced).
Sorry if I went off topic a bit, I answered this kind of question before and just copy pasted my answer here.
DNA is your blueprints to make you either you (versus a chicken as an example). It’s written in a simple language that your individual cell knows how to read and follow, much like an instruction manual.
Here’s the kicker though: languages have stuff besides words that help us follow directions. Think: giant bolding and colors for important stuff, highlighting words, or even someone crossing out instructions that don’t work. That’s epigenetics. It’s the add-ons, that aren’t the instructions themselves, but add on top of the instructions that help your cell follow the instructions better.
Second part of your question: what is responsible? Still under investigation, but some things are inherited from your parents (so if your parents have an instruction manual that highlights special details in parts of “Chapter 7:How to Make a Kidney”, you probably do as well). Some things are somehow programmed in depending on your age (example: once you made a kidney, “Chapter 7” isn’t useful anymore, so your cell will cross out that chapter so you don’t use it again).
The central dogma is that DNA is transcribed to mRNA and mRNA is translated to proteins. And you have proteins that do parts of the transcribing and translating and everything else in the cell. It’s more involved than that, because each step is regulated by a lot of different elements.
But on the whole, proteins are the main actors in the cell. Proteins outside the cell will detect an issue and transmit that information through the actions of other proteins. And they’ll tack on or edit chemical compounds, not just on DNA, but on other proteins too.
DNA is wound around proteins called histones and these histones will assemble differently depending on their specific sequence, either blocking or enhancing access to genes.
The answer is that proteins coded by DNA then add little extra bits to other pieces of DNA. Those little bits are the epigenome.
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