In what way does position effect variegation (PEV) of Dr...

Question

In what way does position effect variegation (PEV) of Drosophila eye color indicate that chromatin state can affect gene transcription?

Accepted Answer

Hi, everyone. Welcome back. Let's look at our next question. It says, what effects does open chroma tin have on gene transcription? And here's our answer. Choices. Choice. A it prevents transcription. Choice be it has no effect on transcription. Choice. See it enhances transcription or choice de depending on circumstances, it can either stimulate or inhibit transcription. So let's recall what is meant by open chrome A tin. And we recall from our condom videos that chromatic kind of exists in two forms open and condensed and they have names. The open chrome button is you crow maten while the condensed protein is hetero commenting. And this is fairly straightforward to remember if you imagine your condensed chrome aton is wound really tightly packed in really tightly. Um And you're open chrome Aton as sort of loose and open because we know that for gene transcription to take place, we have to have access to the D N A. So the regulatory proteins and transcription factors need to be able to actually bind to their sites on the D N A then allowing RNA polymerase to bind. So if you just kind of imagine, you know, sort of a packed in tight ball of D N A versus sort of more open, loosely packed. It's pretty straightforward. Remember that the U chroma tin, open chrome A tin allows access four transcription factors, regulatory proteins, RNA polymerase combined. Since most of those factors work by enhancing the binding of RNA polymerase who are allowing it and transcription takes place. Whereas the contents chroma tin means that all of these things don't have access to their DNA binding sites which blocks transcription. If we have trouble remembering, which is you crow maten and which is hetero chroma tin, it's helpful to remember that that prefix you, you is a good prefix. Um So it refers to things being well made or well done. So if we think of you crow metin, the good kind of coma tin. So with that in mind, we look at our answer choices and it's pretty easy to pick choice. See it enhances transcription. We know that it doesn't prevent transcription. That would be the closed chroma tin. So we can eliminate choice a and choice be it has no effect on transcription. Uh Very much does since it allows all those regulatory proteins, transcription factors to get in to promote transcription. And then again, Joyce D says that he can either stimulate or inhibit transcription. Well, there are other factors that get involved in regulating transcription on top of whether it's open or closed things like DNA methylation, modification of his stones. But that isn't whether it's open or closed. So if we're just talking about what is the effect of the chrome Aton being open, that would be to enhance transcription. So we can eliminate choice the saying depending on the circumstances, it can either stimulate or inhibit. So again, what effects does open chroma tin have on gene transcription choice? See it enhances transcription. See you in the next video.

In what way does position effect variegation (PEV) of Drosophila eye color indicate that chromatin state can affect gene transcription?

Key Concepts

Position Effect Variegation (PEV)

Chromatin Structure

Gene Transcription Regulation

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