During what genetic process are lampbrush chromosomes present in vertebrates?

Video transcript

Hi everyone. Let's take a look at this practice problem together, blank chromosomes are formed during the diplo teen stage a pro phase one of my Asus cell division. They are a special type of chromosome found in the developing oocytes of most animals except mammals. So we are looking for a type of chromosome that's special. It is found in most animals but not mammals and should occur in pro phase one of mitosis. So let's take a look at our options. We've got a palatine. Now this type of chromosome is extra large and recall that it's found in insect salivary glands like Drosophila and they are produced without cell division. So there's no cell division occurring. But you get repeated rounds of DNA replication and so they get extra large. But because there is no cell division occurring, this cannot be our answer. Now we'll look at be supernumerary. Now these are also very large and they are an abnormal type of chromosome found in humans. And so these do not occur normally in cell division and they actually only occur in .0.06% of humans. And so b. Is also not the correct answer. Since this is a type of chromosome found in mammals. Now we're going to look at D. Giant chromosomes and these are very large chromosomes made up of thousands of strands of D. N. A. The name giant and there's two types, there's both the palatine and the lamp brush, which we haven't discussed just yet. But we will in a second. And since it includes the subtype politan chromosome, we can eliminate it because remember politan chromosomes happen without cell division occurring. So now we'll take a look at sea lamp brush. Now they are transitory meaning that they're only found in the dip lutein stage of pro phase, one of my closest cell division. Thus you get this special type of chromosome that stated in our question. Now the name comes from their shape. They're a location of active transcription. So when transcription occurs you get this loop that extends out on either side on each strand. And they see that this resembles the shape of a lamp brush. And so that's how the name came about. So these loops are where transcription occurs. If you don't know what a lamp brush looks like, just google a quick image of it and you should see the resemblance. So our answer is c lamp brush chromosomes. Alright, everyone, I hope you found this helpful and I'll see you soon for the next practice problem.