Histone Acetylation

by Jason Amores Sumpter
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In this video, we're going to introduce a specific type of chromatic modification, which is his stone assimilation. And so his stone proteins that are found within nucleus OEMs of chrome autumn they actually contain a long polyp peptide tail. And this long polyp peptide tail that extends off the histone proteins can actually be chemically modified by cellular enzymes. And the most common modification to the histone protein tales is assimilation. And assimilation is just the process of the addition of an acetyl group, and you can see down below in our image. And acetyl group is just a specific type of functional group, the one that you see right here and in our image down below. We're going to represent assimilation and acetyl groups by using a star symbol to represent the assimilation. Now his stone assimilation actually impacts the chromosome structure because what it does is it loosens the chromosome structure, and that helps the chromosome take on a you crow Metin formation, making the D N A accessible to RNA polymerase and allowing that DNA to be transcribed at a high rate. And so in our example down below, noticed that we're focusing on how histone assimilation loosens the chromosome structure forming you chrome button. And so if we take a look at our image down below again on the left hand side, we're showing you are miniature version of the map. And, uh, you can see that chromatic modifications, which include his stone assimilation, is going to take place within the nucleus of the eukaryotic cell. And so here, what we're showing you is the chrome eaten in a hetero chroma to inform where the nucleus OEMs are really tightly packed together. But notice that extending off of each of these his stones are these little tails and these are called the histone tails. And these histone tails are capable of being modified by cellular enzymes. And so, in this formation over here, the hetero chrome button, the D. N A. Is basically in an off state, and it's not going to be transcribed very much. However, through a simulation which is represented by this arrow right here, assimilation can help turn the d n a into an on confirmation the chromosome structure into an on confirmation because it changes the crow Metin two au chromosome state where it is more loose, and, uh, the D N A. Is more accessible to RNA polymerase and more accessible to transcription. And so you can see the little stars here on the histone tails represents the assimilation, and the assimilation again is going. It's going to be a way to help, uh, allow for transcription to occur. Now, removal of the acetyl groups in a process called D assimilation is actually going to result in the opposite. It's going to result in tight packing of the chromosome structure, basically reverting the chroma team back to the hetero chromosome state. And so on the left. Over here we have the hetero chrome button, which we talked about in our last lesson video. And over here on the right, we have the You Crow Martin and notice that assimilation will help promote a U chromosome state where transcription is more active and then D assimilation is going to promote a hetero chromosome state where the D. N A. Is not going to be transcribed as much. And so his stone assimilation is a chroma tin modification that can occur to help regulate gene expression. And so we'll be able to get some practice applying this as we move forward in our course. So I'll see you all in our next video