Transposable Elements in Prokaryotes

Hi in this video, I'm gonna be talking about transpose herbal elements and pro carry outs. So pro carry out ICC cells. They have two types of transpose herbal elements. The very first type is called an insertion sequence. And what is an insertion sequence is going to be a short bacterial DNA sequence that jumps around the genome because it's a transportable element we know transposing elements jump. So the important part to know about all transportable elements, all of them pro carry attic ones. Eukaryotic ones doesn't matter is that there's an enzyme that allows them to jump. And this enzyme is called transposes and this is the protein that's required for movement of the insertion sequence. But it's also important for movement of all different kinds of transportable elements. And so we're gonna see that different transportable elements um Control transpose is a little bit differently. But we're going to talk about insertion insertion sequence. And so an insertion sequence has two main structural uh features. The first is that they contain inverted repeat sequences at each end. And these are actually a very common feature. And transportable elements. And these repeats are required for the gene to be able to jump. So, super important one. And then the second is the transpose X. And an insertion elements. How they control that transposes activity is they actually encode it between the inverted repeats. So what this looks like is if you look at it here's an inverted repeat and you can see why it's called that way because these are inverted repeats. Right? This is the same sequence but backwards over here. Um And if this was an insertion sequence, the transpose is jean would sit here and when this is transcribed the transposes would be transcribed with it be processed translated produced into protein. And that would come in and cut out outside of these inverted repeats. So that's insertion sequences. The second type is called just a transpose on and that's probably what you're more familiar with hearing. Um And these are longer D. N. A sequences compared to the insertion. All elements that also um jump around the genome. And there are two types of these. So the first type of transpose on is called a composite transposon and composite transposon are flanked by insertion sequences. And so I said before insertion sequences were flanked by inverted repeats but composite transposon is actually had two insertion sequences on either end. And the the insertion sequences which we talked about before and code transpose is this composite transpose sins don't actually encode for transposes themselves. They have the insertion sequences on either side that encode for transpose is so they don't need to. So this is how composite transposing handle transposes differently. And then there's different genes that sit in between those insertion sequences. The second type is the simple transpose on. These are flanked by inverted repeats and that's around jeans that include transposes. And this looks much more similar to insertion sequences except they tend to be longer. Um But this looks very different. So um generally the important part about transposon is we always talk about drug resistance in bacteria right? It's a big thing in the news right now is these superbugs. Well generally drug resistance is actually conferred um and transferred between different bacteria based on transposes scenes found on these bacterial are plasmas. Um And that's just a fun fact. You don't necessarily need to know it but just fun fact transfusions are really what's responsible for these superbugs that we are developing now. So here we have a composite transpose on. These are the insertion sequences. Remember the insertion sequences and code for transposes. So they're already present here. So we don't need transposed in the jeans and the simple transpose on instead has inverted repeats. The inverted repeats don't have transposes themselves. So the transposition has to actually encode for transpose eyes. So you can see that here in red now transpose on. So we're still in this second type of transportable element. So transpose on transpose that's the verb of actually jumping. Um In two main ways you see that we're liking the two pattern here. So tran and within transpose on there's two ways to jump and the first is called replicated transposition and that is why and the trans pros on is actually copied. So it's replicated and then the new copy travels to the new location while the old copy remains in the same location. So you can think of replicated transposition as copy and paste. So now after this copy and paste this happened there's now two of the exact same type of transpose isn't just located in different regions of the genome. Then the second type is conservative transposition. And this is where the transposon is cut out and moved to a new location. So this is the cut and paste method where after the jump you still have the same number of transpose since it just moved to a new location. So the two types of the copy and paste and the cut and paste and those are make sure you understand that difference. So if we have the copy and paste method, what happens is this gets replicated and this old one stays in the same spot and the new one goes moves somewhere else in the genome. Whereas conservative transposition. If you start out like this what happens is it's just cut out and it and it moves to the new location where you still only have one copy And this you end up with two copies. So the copy and pace and this is the cut and paste method. And obviously those have different impacts on the genome where this one keeps replicating itself, getting more and more copies where this one it always stays the same number of copies. Um So with that let's not move on

Transposase is a protein that is responsible for what?

• A. Excising a transposable element from a donor site
• B. Insert a transposable element into a target site
• C. Degrading a transposable element that is harming the host genome
• D. Amplifying a transposable element

Which of the following transposons do not encode for the transposase enzyme?

• A. Insertion sequence elements
• B. Composite transposons
• C. Simple transposons

Which of the following sequences is an example of an inverted repeat sequence that would surround one strand of an insertion sequence element?

• A. 5' AATCG CGATT
• B. 5' AATCG AATCG
• C. 5' AATCG TTAGC
• D. 5' AATCG GCTAA