Chromosomal Rearrangements: Duplications - Video Tutorials & Practice Problems

Duplications

Hi in this video we're gonna talk about chromosomal rearrangements and focus on duplications. So duplications are exactly what they sound like. It's where you have a chromosome segment and it's doubled. And so there are many different types. There could be tandem duplications. And these are when the duplicate region. So the normal the original region and then the duplicate are adjacent to each other. You have insertion all duplication. And this is when the region. So the normal and the duplicated are located somewhere else. They're not adjacent. They're far apart from each other in the genome. And then you have very large segmental duplications which are very large. 10-50 killer basis and encompass very large sections. Um these are more rare. then um and occur only mainly in a few organisms. So these are the two really main important ones to know. So here is an example of a tandem duplication. So you can see there's an extra copy of jean B. Um and it has occurred and right next to each other to adjacent. Um Here's an insertion of duplication which again there's a copy of jean B. But you can see that it's located elsewhere, far apart from each other on the chromosome. Um An insertion all duplication can actually occur on other chromosomes as well. Then draw that here and do it on the same but it can occur on the same or other chromosomes. Now duplications are extremely important in evolution. One of the main examples of this is actually our D. N. A. So what is our D. N. A. While our D. N. A. Creates R. R. N. A. Which if you remember what our RNA does it creates the rival zone, right? Our ribs. Oma RNA. This is really important for the rebel zone. Now there are so many ribosomes right? Like in humans we have so many ribosomes in every single cell. There's so many of them that if there was just one copy of this, our D. N. A. Gene we would not be able to survive right? Like we have to have so many copies of these are DNA genes in order to create enough ribosomes to support the protein synthesis that we need to live. So if the our DNA gene had never duplicated we couldn't survive. And so the duplications that occurred to this. Our DNA gene are super important for making sure that we have the ribosomes available to do the protein synthesis that keeps us alive. And so this is a super important uh duplication and evolution connection. Another one is that duplication actually results in three copies of an L. Right? So if you normally have these two alleles let's say the dot. And so these two are important, right? And the organism will evolve however it's going to evolve. But essentially these genes need to stay functional right? Because if they're not functional that could kill the organism or cost them weird mutation that has weird phenotype that prevents it from living or growing or reproducing or whatever. So generally these are pretty restricted on evolution. They have to stay fairly the same over time and they're not as free to evolve. But if you have a duplication, so you copy this khalil here now you have three alleles. So you have the two that are required for life and now you have this third that isn't required and therefore is free to change over time. So it can mutate all all over the place and eventually become a completely different level. And so this is the process of evolution with my pen. But essentially, you can imagine right mutations are more likely to develop in this third Ulliel because it's not necessary, right? It was just a duplication. If it's not there, the organisms still going to survive grow. But because it's there, it can mutate. And sometimes those mutations will be really beneficial and they just keep mutating, keep mutating and eventually become something completely different. That's super useful for the organism doesn't happen every time, but it definitely can happen. So that's how duplications are really important for evolution. So with that, let's move on.

A person has a WT chromosome with the following segments. A B C • D E F G H. Which of the following shows how the chromosome would look after an insertional duplication?

• A. A A B B C • D E F G H
• B. A B C • D E F G H A B
• C. A B A B C • D E F G H
• D. A C • D E F G H

A person has a WT chromosome with the following segments. A B C • D E F G H. Which of the following shows how the chromosome would look after an tandem duplication?

• A. A B B C • D E F G H
• B. A B C • D E F G H B
• C. A B A C • D E F G H
• D. A C • D E F G H