Give descriptions for the following terms: heterochromatin

Question

Accepted Answer

Hi, everyone. Welcome back. Let's look at our next question. It says all of the following are features of heterochromatin except and before we look through our answer choices, let's just make sure we recall uh what the distinction is between the two forms of chromatin. So we have that in our minds before we evaluate our answer choices. So heterochromatin, we recall is the tightly packed form of chromatin versus U chromatin, which is loosely packed. And the main implication of this is that euchromatin contains the genes that are highly transcribed. That loose packing means that the transcription machinery can get in there and transcription can take place. Whereas the tightly packed heterochromatin is almost impossible for transcription enzymes to get in there. And genes present in that region tend to be silenced or expressed at extremely low levels. So with that straight in our mind, let's go through our answer choices and evaluate them. Remembering that we're looking for the statement that is not a feature of heterochromatin. So choice A says tightly packed and condensed form of chromatin that appears as a darkly stained region under a microscope. Well, this is true about heterochromatin. And so it's not our answer choice. Joyce B says composed of highly repetitive DNA sequences such as satellite DNA and trans posible elements. Well, this is also true about heterochromatin. Um This these DNA sequences in here. Um There's not so many genes in there but contains many, many of these repetitive DNA sequences. And so that's not our answer choice either. And choice C says involved in maintaining the structural integrity of chromosomes and genome stability by preventing recombination and transposition events. So this isn't useless. Uh DNA, despite it not having many genes that get transcribed, it is involved in maintaining the structural integrity and genome stability. So this is also a true statement and therefore not our answer. Finally, choice D contains genes involved in cellular processes that are essential for the survival of the organism. Well, this one is false um because the genes present in heterochromatin are either not expressed or expressed very little. You would not want genes to be in there that are essential for the survival of the organism. Those would be in the loosely packed EMA which is accessible for transcription. So choice D is our answer as the feature. The one statement that is not a feature of heterochromatin. So choice D contains genes involved in cellular processes that are essential for the survival of the organism. See you in the next video.

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Give descriptions for the following terms: heterochromatin

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