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Say my mom has blue eyes and my dad has brown eyes. What color would my eyes be?

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Now for a long time people thought that the color of my eyes would just be a

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mix of the color of my parents. So it would be a mix of blue and brown so some

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kind of a dark brownish bluish eyes and that's what they believed for every

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single trait. So for example my mom has straight hair and dad has let's say

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curly hair then again they believed i would get a mix of them kind of straight kind of curly wavy

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hair and so for a long time people thought this is how traits get passed or inherited from parents

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to children it'll just be a mix the traits will just be a mix in the children but is this really

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how trades gets passed on who's going to answer this question well there was one man actually a

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monk named gregor mendel who decided he's going to answer this by growing a lot of pea plants

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in his garden now if you're wondering why he chose pea plants then we've talked a lot about this in

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a previous video talking about how pea plants have a lot of characters to experiment with

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and how these characters have only a couple of traits and all of that so if you need a refresher

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it'll be a great idea to go back and watch that video on which is called why Mendel chose pea

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plants okay but if you feel you're cool with this then let's go ahead and see what kind of

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experiments Mendel performed on these pea plants so Mendel performed a lot of experiments on

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different characters right so let me take one example the character height so what he would do

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in one of his experiments is he would take a pure tall pea plant and then cross fertilize it

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with a pure short pea plant and then see what offsprings they would give now i'm pretty sure

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you may be wondering what do you mean by pure plants what does this pure mean pure basically

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means if you were to self-pollinate them, so if you were to self-pollinate a tall plant, it should

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give all tall plants. If you self-pollinate a short plant, it should give all short plants. And what do

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you mean by self-pollination? Well, suppose this is one of the flowers of the tall plant. Now, what I

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mean by self-pollination is you take the, what do you call this, pollen grains, yeah, you take the

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pollen grains from the flower and put it back into the carpel of the same flower. Basically, you

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put it back into the female reproductive part of that same flower and then it'll grow seeds and

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then you sow those seeds and then if you find that all the seeds grow into tall plants then that then

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we will say this is a pure tall plant this is the meaning of pure and similarly if you were to do

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the same thing for the short plant as well so you take one of the flowers of that short plant and

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then you self-pollinate meaning you take the pollen grains put it back into the same flower

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let it fertilize and then you grow seeds and you sow them and if you find all of them grow into

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short plants not a single tall plant but all of them grow into short plants then we will call this

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a pure short plant okay so mendel prepared these pure breeds for his experiment a pure tall plant

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and a pure short plant let me get rid of these now and so for his experiment you know what he does

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he cross pollinates them meaning he takes the pollen grains from one of the plants and he puts

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it into the flower of the other and you can take it from anyone to anyone so for example he might

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take the pollen grains of flower from the tall plant and then put it into the carpel or the this

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part of the short plant so let's say he cross fertilizes them like this and then this will

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start growing seeds then he sows that seeds to see what we will get after this cross fertilization

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so what do you think we will get well let's get rid of the flowers and make some space

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so what do you think we end up with well i would expect to get some medium height plants right

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because you have a short one you have a tall you have a tall one you have a short one so maybe they

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get mixed and you end up with all medium-sized plants. That's reasonable to think, right?

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But to Mendel's surprise and to even my surprise when I learned this, we get all tall plants.

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What? That's right. Big shock. 100% of them, 100% of them end up being tall.

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this raises many questions what happens to the short one does it have no effect at all

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why aren't we getting any medium-sized plants why aren't we getting any short plants what is going

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on anyways he addressed these plants as f1 generation plant this is the name that he gives

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them and if you are wondering why he called them f1 the word the f stands for a latin word filial

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I hope I'm pronouncing that right it means son or daughter okay so that's why this these plants

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are called f1 generation first generation sons and daughters of these you can say but yeah

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Mendel was shocked by this so he didn't stop over here he started asking questions one of the main

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question he was asking is are these plants these tall plants the same as the parent tall plant

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are they same they look the same because they have the same height but are they really the same

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is this also a pure tall plant that's the question he started asking and to answer that question you

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know what he did he did another experiment he didn't stop over here what he does next

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what he does next is he takes one of the f1 generation plant which is basically tall

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he takes one of the f1 generation plant this is f1 generation oops let me use this white color

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So this is F1 generation and he self-pollinates it, self-pollinates it to see what we get.

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So again, it'll grow seeds and then he sows that seeds.

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What do you think we'll end up with?

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Well, surprise, surprise, now some short plants are found.

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Another shocking thing to see, right?

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Because again, where did these short plants come now from?

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Certainly, right?

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and guess what Mendel even counted them so in this f2 generation this is the second generation

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sons and daughters or offsprings what when he counted them you know what he got he found that

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there were roughly three times as much tall as you had compared to short so the tall to short

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ratio was three is to one and if you're wondering yes he also cross-pollinated the f1 generation

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plants and he gets exactly the same result three to one and you know why this number is so important

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because it's not random it turns out he gets the same answer for all the characteristics that he

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experiments with i mean for example when he takes when he takes the color of the flower into

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consideration again he takes a pure purple colored pea plant and crosses it with a pure white pea

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plant in the first generation you know what he gets a similar result this time he gets all all

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purple colored flower no yellow no white flowers at all but then when he takes one of these f1

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generation purple flower and self-pollinates guess what he gets he now gets uh three times as much

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purple as white white comes back it's in minority some small amount three to one ratio but it comes

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back with the same ratio, 3 is to 1. So what's going on? Why didn't we see the white flower over

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here, but somehow it comes back in the next generation? What is going on? Before we think

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of what's really going on, one thing is very sure. Our initial assumption that traits get mixed and

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sent to their children is absolutely wrong, isn't it? I mean, if that was the case, we would have

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found some medium plants over here. Or over here, we would have found some pinkish colored flower,

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mix of purple and white but we don't get that so mendel from his experiments conclusively proved

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that traits do not get mixed at all that in itself was a huge discovery but now he had to figure out

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what it all meant and i'm going to leave you here hanging with this question as mendel must have

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been left hanging with we will look at the exciting conclusion of what all this means

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in the future videos. Meanwhile, ponder on this for a while.

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See if you can come up with any theory to explain this.