What are the different chromatin classifications, and what is ...

Question

What are the different chromatin classifications, and what is their relationship to gene expression?

Accepted Answer

Hi, everyone. Here's our next question. It says which of the following types of chromatin can switch between a condensed and less condensed state depending on the needs of the cell choice. A facultative heterochromatin B constituted head of chrome C U croton or D, both A and B. Well, first of all, we want to recall that the condensed version of chromatin is the heterochromatin. It's less accessible for transcription. So in general, there are not many genes present in that form of chromatin. And the form is the U chromatin where it's more loosely packed structure makes it accessible to transcription factors. R N A polymerase allowing genes to be transcribed. So with that in mind, let's go through these answer choices. We noticed that there's two types of heterochromatin facultative and constituted well, the meaning of constitutive, it can remind us of constant means a constant level. We can think of a constitutive gene expression. The gene is always turned on. It doesn't vary with the environment surrounding it. Whereas facultative means something exists in more than one state. And again, you can think of using these terms when you've talked about forms of gene expression where facultative expression would be gene expression that varies depending on its environment. So that can really help us to point to if we're looking for a type of chromatin that can switch states, that gives us a clue that we're looking for. Choice. A facultative heterochromatin. And yes, that is the correct answer. This is heterochromatin that's able to switch between condensed and less condensed depending on the needs of the cell, whether it needs those genes or not. And an example is the inactive X chromosome in female mammals, which is in the form of facultative heterochromatin. Since one of those X chromosomes needs to be turned off in each cell of the female body. But the other X chromosome needs to have its genes expressed. So that's a situation where it's an advantage to have the Chromos chromosome. Be able to exist in the less or more condensed version. Just looking through our other answer. Choices. Choice B constituted heather chromatin as we can assume based on that name constitutive always exists in that condensed form. And that would be chromatin that consists mostly of repetitive DNA sequences. So again, it's not going to contain genes that need to be transcribed. And then choice C U chromatin is chroma that just chromatin that just exists in this less condensed form to be able to be accessible for transcription. So that's not our answer. And then also that means choice D both A and B is incorrect since we know that B is not our answer. So again, which of the following types of chromatin can switch between condensed and less condensed depending on the needs of the cell choice. A facultative heterochromatin. See you in the next video.

What are the different chromatin classifications, and what is their relationship to gene expression?

Key Concepts

Chromatin Structure

Gene Expression Regulation

Epigenetics

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