Describe the two types of transcription termination found in bacterial genes. How does transcription termination differ for eukaryotic genes?

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Welcome back, everyone. Let's look at our next problem. It says factor independent transcription termination and bacteria requires the presence of choice a, a stem loop structure in the R N A transcript B A G C rich sequence followed by a series of a residues in the DNA template strand choice C A poly, a signal sequence in the DNA template strand or choice D A termination factor called the row factor. Well, even if I didn't recall the specific details here, I can actually eliminate one answer choice right off the bat. Choice D says we require the presence of a termination factor called the row factor. But we know right in our problem that it's talking about factor independent transcription termination. So by definition, being factor independent wouldn't require a termination factor. So indeed, we can eliminate choice D, the row factors involved in factor dependent transcription termination in which are R N A transcript has a binding site for that. A row factor protein which climbs the R N A transcript until it meets up with R N A polymerase and pulls apart the R N A and DNA strands terminating transcription. But we're talking about factor independent termination, which does not need an outside protein but involves the R N A polymerase alone based on a DNA sequence. So what's required of our DNA sequence for transcription termination to occur? And the answer is we have a G C rich sequence that when it's transcribed causes the R N A transcript to form a hairpin structure. All those GS and CS cause the R N A strand to form a complementary binding with itself forming this hairpin or stem loop structure that results in the R N A polymerase stalling at this point. Following that G C rich sequence, you also need a series of a residues in the DNA template. A residues in the DNA template are going to result in a series of U residues in the R N A transcript. And the A U binding in that region will be very weak as a result, the DNA and R N A strands pull apart, terminating transcription. So you have these two things that are interacting with each other. First, the G C rich sequence forming that hair pin that stalls the R N A polymerase. And then that series of a residues that forms this region of weak U A binding that pulls apart that results in the pulling apart of the DNA and R A strands. So let's look at our other answer choices that we haven't eliminated yet. Choice A says a stem loop structure in the R N A transcript. Well, we do require that stem loop structure which forms as a result of the G C rich sequence. But that's not sufficient. We need both of these elements here. So we're going to eliminate choice A, not that it's incorrect, but it's not sufficient. Choice. B says A G C rich sequence followed by a series of a residues in the DNA template strand that is correct. Those are the two factors that are necessary that to be the will look at choice C which has a poly, a signal sequence in the DNA template strand. Again, that's one of the things that's necessary but not sufficient. Both are needed. We also need the G C rich area that forms that hair pin structure. So choice C is not a complete answer to what we're looking for. So again, factor independent transcription termination in bacteria requires the presence of choice B A G C rich sequence followed by a series of a residues in the DNA template strand. See you in the next video.

Describe the two types of transcription termination found in bacterial genes. How does transcription termination differ for eukaryotic genes?

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Key Concepts

Transcription Termination in Bacteria

Eukaryotic Transcription Termination

Differences Between Prokaryotic and Eukaryotic Termination