Eukaryotic Chromatin Modifications

by Jason Amores Sumpter
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in this video, we're going to begin our lesson on Eukaryotic chromosome modifications. And so eukaryotes can regulate gene expression by modifying the structure of their chroma tin. And so recall from our previous lesson videos that Crow Mountain are loosely packed or uh, loosely coiled nuclear zones, which is basically just d n a wrapped around units of eight histone proteins. And so, if you don't recall this, then make sure to go back and watch those older lesson videos on D N A. Before you continue here. Now, modifications to histone proteins or modifications to the DNA sequence itself can actually impact uh, the transcription process. And so, uh, histone modifications and D n A sequence modifications are made to control transcription. But these modifications are taking place at the chromosome level, affecting the histone proteins or the D N. A sequence. And really this leads to two different types of chroma tin. It leads to hetero chrome button, and also it leads to you Crow Metin, now hetero chrome button, is going to be a condensed region of the genome with really, really low transcription activity, and so hetero chrome button is not going to be transcribed and you, Crow Metin is basically the opposite is a lightly packed region of the genome with high transcription activity and histone and DNA modifications. And so, if we take a look at our image down below, uh, we can distinguish between Hetero Crow Mountain and Ukraine Martin. And so again, over here on the left hand side, we have this miniature version of our map of the lesson. And again, we're starting off with chromatic modifications, which is going to take place in the nucleus sense. That is where the Crow Mountain is found, and so hetero chrome button is basically like turning off the light switch. It turns off transcription and turns off genes, and so it's going to represent really, really tightly packed Um uh, chromatic heteronormative is super super tightly packed, and that's going to have really, really low transcription all activity. And this is simply because the transcription machinery, like RNA preliminaries and things of that nature will not be able to fit in access the DNA that it needs to access because it's so tightly packed and so hetero. Crompton. This tightly packed D N. A is a way to lower transcription activity and turn off genes a form of regulation. Now you chrome button, on the other hand, is a way to turn on the light switch to turn on genes so that transcription activity is high. And so notice that over here the chrome button is much more loosely packed. And because it is loosely packed, it's going to have high transcription ALS activity. And so you can see that the transcription machinery like Arnie Proliferates, for example, is capable of accessing the DNA that needs to be transcribed. And so because the D. N A is loosely packed, it's going to have high transcription of activity, and that is a way of turning on the genes. And so this year concludes our brief introduction to Eukaryotic chromosome modifications. But as we move forward, we're going to continue to talk about specific modifications that can take place that will lead to either hetero Crow Mountain or you crow Martin. Uh, and so I'll see you all in our next video