In this video, we're going to introduce short tandem repeats, which are commonly abbreviated as STRs. And so genetic markers used by researchers are generally made up of short repeat sequences that vary in number. And so these are referred to as short tandem repeats, which again are commonly abbreviated as just STRs. And so these short tandem repeats or STRs are short repeated sequences of DNA that are approximately 2 to 5 nucleotides long. Nts is an abbreviation for nucleotides, and they're found in very specific regions of a genome. Now the specific number of STRs or short tandem repeats within this region of a genome is polymorphic, which means that it is going to be unique for each person and each individual and can be used to identify an individual. And so here in this example image down below, we're showing you just some examples of short tandem repeats. And so short tandem repeats or STRs are genetic markers that can be used to identify an individual, perhaps, identifying the individuals, by using DNA that's found at a crime scene. And so it can be used to help solve a crime.
And so if we take a look at this image down below, notice that the repeated sequence, the short, tandem repeat that we're looking at is, this sequence right here where it is g a t a. Okay? And so this is the, double stranded DNA and the short tandem repeat that we're specifically focusing on in this image. And so what you'll notice is that we've got DNA from 3 different individuals down below. Individual one's DNA is here. Then we have individual 2, their DNA is there, and individual three's DNA is at the very bottom. And what you'll notice is that at this very specific region of interest in the chromosome, each of these 3 individuals differ in their number of short tandem repeats or STRs. And so what you'll notice is that individual number 1 has a total of 5 STRs, five short tandem repeats, which would be unique to this specific individual number 1. Individual number 2, notice it only has 3 of these short tandem repeats within this region of the genome. And that 3 would be unique to individual number 2. And individual number 3 has a total of 4 short tandem repeats. And so the number of short tandem repeats is going to be unique for each individual and is going to be a genetic marker that can be used to, again, identify an individual and can be used to, basically help solve a crime by comparing the, the DNA that might be found at the crime scene with the DNA from the suspects.
And so, this here concludes our brief introduction to short tandem repeats or STRs, and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.