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in this video, we're going to begin our lesson on DNA fingerprinting. And so DNA fingerprinting is really just a specific technique that is going to be using genetic markers within a genome to identify an individual. And so, just like a fingerprint can be used to identify an individual like the fingerprint that we have down below right here. Uh, DNA fingerprinting can help to identify an individual. And so what are these genetic markers? Well, genetic markers are, uh, sequences of D N A with a known location and are easily identifiable in a genome. Markers are specifically referring to Polly Morph ISMs and polymorphisms are completely different between the genomes of each individual. So their differences in the sequence across different individuals. And so, for example, a single nucleotide polymorphisms, which are commonly abbreviated as SNPs or snips our genetic markers in a genome that differ by just one single nucleotide across different organisms. And so, if we take a look at this example image down below, we're looking at how a single nucleotide polymorphism, uh, can exist between two folios, uh, within the same organism across two different, uh, individuals. And so if we take a look at this image down below. Which will notice is that we have, uh, individual number one, which is right here. And this is the specific D n a sequence of individual number one and down below. We have individual number two who's sequences right here. And what you'll notice is that the D N. A sequence of individual one an individual number two are pretty much exactly the same. Except for this one position here of this, uh, this base pair. And so this would be referred to as a single nucleotide polymorphism or a snip, because it's just this one position here that is going to differ between the two, where individual one has a T a base pair at this position, whereas individual to has a C G base pair. And so these polymorphisms are going to be unique to specific individuals and can be used to help identify an individual just like a, uh, fingerprint can be used to identify an individual. Now, a DNA fingerprint person's DNA fingerprint is really just referring to the combination of all the unique genetic markers and an individual's genome. And so this year concludes our brief introduction to DNA fingerprinting and how these unique genetic markers and polymorphisms can be used to help identify an individual. And so we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.
Short Tandem Repeats (STRs)
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In this video, we're going to introduce short tandem repeats, which are commonly abbreviated as S. T. R. S. And so genetic markers used by researchers are generally made up of short repeat sequences that very end number. And so these are referred to as short tandem repeats, which again are commonly abbreviated as just S. T. R. S. And so these short tandem repeats, or STRS, are short repeated sequences of D N A that are approximately 2 to 5 nucleotides. Long NTS is an abbreviation for nucleotides, and they are found in very specific regions of the genome. Now the specific number of STRS, or short tandem repeats within this region of the genome is polymorphic, which means that it is going to be unique for each person in 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 SDRs are genetic markers that can be used to identify an individual, perhaps, uh, identifying the individuals by using D N A. That's found at a crime scene and so it can be helped 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, uh, 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 were specifically focusing on in this image. And so what you'll notice is that we've got DNA from three different individuals down below individuals ones D N A is here. Then we have individual to, uh their d n A is there, and individual three's d N A. 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 three individuals differ and their number of short tandem repeats, or STRS And so what you'll notice is that individual number one has a total of five STRS five short tandem repeats, which would be unique to this specific individual number one individual number to notice it only has three of these short tandem repeats within this region of the genome, and that three would be unique to individual number two, An individual number three has a total of four short tandem repeats. And so the number of short tandem repeats is going to be unique for each individual. And it's 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 DNA that might be found at the crime scene with the D N A. From the suspects. And so this year 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.
The goal of DNA fingerprinting is:
To collect DNA samples from random individuals in a population.
To diagnose diseases within closely related family members.
To determine whether DNA samples collected from two different locations are from the same person.
None of the above.
Which of the following characteristics of short tandem repeats (STRs) makes it useful for DNA fingerprinting?
The number of repeats is highly variable from person to person or organism to organism.
The sequence of DNA that is repeated varies significantly from individual to individual.
The sequence variation is acted upon differently by natural selection in different environments.
Every racial and ethnic group has inherited a specific number of short tandem repeats.
The gel below shows a region of STRs from a DNA sample taken from a crime scene. It also shows the same region of STRs from 4 suspects involved in the case. Which suspect’ DNA was found at the crime scene?
They are all innocent.