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Video transcript

what I hope to do in this videos is hopefully give you some clarity on terms that you might hear used in a fairly related way and those are the terms gene and allele gene vs. allele so let's do a little bit of review let's just reorient ourselves in the world of DNA and RNA let's say that this this yellow squiggly line is a length of let us say my DNA and let's say this little white section right over here that's if we were to zoom in and we've represented the various base pairs and this the sequence of base pairs is really the information content in DNA and here I've just kind of drawn it as a as a ladder but we know that the real structure of DNA is it's kind of a twisted ladder this this this double helix now if we talk about this this whole yellow squiggly line and it could be even a section of a longer yellow squiggly line this could code for multiple for multiple things especially multiple proteins so different regions of this could code for different proteins so for example this section right over here could be part of this region that I'm highlighting in blue that codes for a specific protein and so we would call this a gene we would call this a gene this might be a protein that is involved in I don't know I'll make something up it's a protein that's of all involved in the immune system maybe maybe this stretch let me do it in a different color maybe this stretch of DNA right over here this stretch of DNA maybe it's a longer stretch of DNA maybe it codes it codes for a protein that's used maybe it maybe it's a protein that helps regulate DNA replication maybe over here is another we encode for another protein that now may be a maybe it in some ways effects affects the pigmentation of your skin or the pigmentation of your eyes and so you have these stretches of DNA that code for specific things and actually it doesn't have to just even be for a protein we've always talked about even if you do code for a protein you go from the DNA to messenger RNA to messenger RNA next you can you goto pre messenger RNA and that that that gets processed so you can actually can lose some sections of it but you go to messenger RNA and then that messenger RNA every three every three of these base pairs is a codon let me let me so let's say that's one codon one two three that's another codon one two three each of those and maybe I'll draw them next to each other each of them codes for an amino acid that is kind of connected together to form connect it together to form a protein so that's one amino acid right over there this could be another amino acid right over there and now we're going to see we can keep going on and on and on you can have another amino acid right over here and then they all bond to each other and they're brought actually to the mRNA from by a functional RNA group and so there are functional things other than proteins that this could go for like trna T RNA which is really helping to transport the appropriate amino acids to the mRNA in in in the ribosome so that you can construct these proteins so you could have tRNA and we've seen this before in previous videos it's this little squiggly line matches up to the appropriate codon and then puts that amino acid in place you also have things like ribosomal RNA that make up the structure of the actual ribosome so RNA doesn't only have to play this kind of in between messenger function it actually can play a functional or a structural role in fact there are theories that the earliest life the most primitive life was nothing but self-replicating RNA and then the systems became more and more and more complicated and more complex and until eventually you end up with things like redwood trees and hippopotami hippopotamuses hippopotami what elephants well whatever else but it all started with potentially self-replicating RNA some people say might be some type of proteins that were able to replicate who knows but RNA is definitely is definitely an interesting character in this so you go from gene to RNA that's transcription and then RNA to protein to protein that is translation but sometimes you just stop at the RNA and the RNA by itself plays a functional functional RNA so each of these genes they can they can code for type of protein or even a functional RNA that's what a gene is now what about an allele when the allele is a specific variation of the gene so for example let's say that you look at the at the same stretch of DNA let's say this is my DNA and if I were to take your DNA out and if I would look on the same chromosome at the same region where both human beings and we have for the most part very similar DNA so this is actually let me let me straighten it out so let's say this is my DNA a section of my DNA and let's say this right over here this in Y it is a section of your DNA and so if we look at that gene that blue gene that's that on my DNA now if we look at that and this is the blue gene this is the blue gene on your DNA now we're both human beings and most of our genetic material is fairly similar but we might have variations in how this gene is coded for example you might have or I might have a let's say I have a an adenine right there but right at that exact spot you might have a different base you might have a I don't know you might have a you might actually let me just you might have a you might have a thymine right over there so it's encoding for a protein or even a functional RNA that's playing the same role maybe it has a role in the immune system role in your skin color a role in how your brain develops but there is a variation there's a variation in how its coded now some of these variations which could arise through mutations it might not have any impact in the function of the eventual protein that gets constructed you might just have a different amino acid someplace in fact you might not even have a different amino acids because many times you have two codons coding for the same amino acid but even in a case you might have one different amino acid in a protein that has 4,000 amino acids and it doesn't change how that that protein acts or how it functions or sometimes it might it might change how that protein functions it might change how that protein regulates other things and whoever knows whatever else and so you can imagine that you have genes this gene right over here maybe it has a role in eye color and because of this variation or because of other variations said that show up in both cases they code for the protein that say regulates eye color or regulates the amount of pigment you have but because your variation right over here might lead or help Li then these things are very complex it's very seldom that you just have a gene for this but this might make you especially if you have a gene like this from both of your parents maybe this one would go for blue eyes blue eyes it somehow helps produce blue eyes while this while mine somehow helps produce brown eyes and obviously I'd want to think about which with the very the variant of this gene that I get from my mother and the variant of this gene that I get from my father we all have two copies in our in our regular somatic cells in our body cells we have except for if we think about the you know the the X X and the X Y chromosomes the sex-determining chromosomes on all of the other chromosomes we have two copies of the same genes we just have two we it's just they're different variants one variant from your mother one variant from your father or you could say that they are different alleles so alleles are just different variants so these are two different alleles they coat they're the same gene they're the gene that somehow deals with eye color but they're different variations for that gene so the gene you're speaking generally to that region of DNA that region of the DNA strand that in that codes for some functional molecule usually protein but it could be RNA while the allele is that specific variation that flavor of that gene hopefully that helps
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