let's go back in time for a brief minute back to the 1800s we're in a quiet Monastery Garden there's a man there and his name is Gregor Mendo he's an Austrian monk who has a strong curiosity to understand more about life this man Gregor Mendel is known as the father of genetics he spends a lot of lettering his pea plants now not for the sake of eating stew peas like we do in the Caribbean no it's curiosity and interest is much deeper than that he pays special attention to their individual characteristics noticing little things like their variations in height the seed shape seed color flower color and more and he doesn't just stop at observation because his curiosity won't allow that he takes it a level deeper and starts experimenting on these pea plants by asking very interesting questions what would happen if I took towel plants and cross them with short plants how would their offspring turn out or what about it if I took plants with yellow peas and cross them with plants with green peas and just like that he ran a series of experiments cross-pollinating pea plants with different characteristics just to see what would happen and as a curious Explorer he took meticulous notes as he observed What would happened to The Offspring of those cross-pollinated pea plants we refer to The Offspring resulting from this initial cross as the first generation or the F1 generation now here's the thing up until this point Offspring were thought to come from a kind of melding of characteristics from both parents so maybe if you cross plants with green seeds with plants with yellow seeds there'd be a color somewhere in between or maybe they'd have both colors that may have been what Mendel expected but it's not what he observed instead he noticed that in the F1 generation traits seemed to Disappear Completely all of The Offspring were tall or had yellow peas the short and green traits just completely disappeared now you can imagine his surprise I mean that wasn't supposed to happen based on what was thought at the time but like a curious scientist he couldn't just stop there he needed to figure this thing out so he decided to cross pollinate the F1 generation to see what would happen in the second generation we call this the F2 generation and here's where the fascinating Discovery happened in the F2 Generation The Hidden traits reappeared but here's the kicker they didn't reappear in equal numbers there was a very specific proportion when he crossed tall plants that came from tall and short parents around three of every four of the plants were tall and one out of every four was short when he crossed plants with yellow seas that came from Crossing parents with yellow and green seeds the same kind of thing happened approximately three out of every four plants had yellow seeds and one out of every four had green seeds this was a fascinating Discovery and Mendel tried to make sense out of his findings and this is what led him to formulate some laws that have become fundamental to our our understanding of heredity now lean in because this is the important part of the video we're digging into these fundamental laws of heredity the first law of heredity is the law of segregation this law states that a gene can exist in multiple forms these forms are now known as alleles let's take the seed color as an example there is a gene that calls for the seed color of the pea plant and there are two alleles that code for seed color one allele codes for yellow seed color and we'll have that as a capital Y and the other allele calls for Green Seed color and we'll have that as a lowercase y now when a sex cell is formed these alleles will separate or segregate so that each sex cell AKA gamete will have one single allele for each trait so in this case it'll either have a capital y or a lowercase y yellow or green and when fertilization happens The Offspring will then have two use for each gene one from each parent it makes sense this is the law of segregation the alleles will segregate when gametes form only to come together when fertilization happens let's move on to the next law the next law the law of dominance states that alleles for a trait can be dominant or recessive so if an individual has two different alleles for a trait the dominant allele can mask the expression of the recessive allele with Mendel's P plans for example the allele for purple flowers was dominant and the allele for white flowers was recessive so if a pea plant had one allele for purple flowers and one for white flowers the flowers would be purple since that was a dominant allele essentially the purple flower allele would mask the presence of the white flower allele so that's the law of dominance an allele can be dominant or recessive and dominant alleles can mask the presence of recessive alleles now the final law is the Law of Independent Assortment this law states that different traits are passed on to offspring independently of each other imagine you're at a restaurant and you're ordering a meal the choice of your entree doesn't affect your choice of dessert so you could order steak with ice cream or fish with cake wait now I'm hungry in the same way the alleles that a gamete receives for one gene doesn't influence the allele that it receives for another Gene they're received independently from one another that's why in Mendel's experiments a plant's height didn't affect the color of the seeds or the color of the flowers it could be tall with green seeds or it could be short with green seeds and that's the Law of Independent Assortment now our understanding of genetics has grown significantly since Mendel's time but his findings were and still are a big deal they give us a lot of insight into how heredity works and as we continue in this series we're going to explore things like how these laws apply to humans how genetic disorders can occur and we'll even look at the exceptions to these laws because while Mendel's Laws give us a strong Foundation it turns out the field of genetics is a lot more complex and even more fascinating than Mendel thought at the time so let's continue on in this exciting genetics Journey my name is Leslie Samuel from interactive biology where we're making biology fun that's it for this video and I'll see you in the next one