Non mendelian inheritance 5- Polygenic traits
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Non mendelian inheritance 5- Polygenic traits


– Polygenic traits.
Polygenic. Most of the traits
in you are polygenic traits. Poly, many, genic,
genes. Many genes contribute
to one trait. And an example
of this is eye color. And I know I always use the blue
eye brown eye allele example, which I hope I always remember
to say is totally not true. But, in fact,
at this stage of the game, I’m my knowledge is
that there are three genes that contribute to eye color, which is how you end up
with a varying shade, which is why none
of our eye color, like, analyses ever work out, because it really isn’t, it’s not just simple
Medelian genetics, one gene on one
chromosome creating this particular phenotype. Three different genes that are interacting
to create this phenotype. Now, we’re about to get
into some situations where it really does start
getting pretty messy. Right now, I can look at you
in the eye and say, yeah, three genes,
code for eye color. But by the end of this, hopefully you realize
that that’s, like, sometimes,
and sometimes not so much. All right, so polygenic traits,
one trait, multiple genes contributing
to that. Another example
of polygenic trait is height. There are multiple genes that are contributing
to this phenotype. Often, with polygenic traits, you end up with a sort
of bell curve of diversity, of possible
different phenotypes, as opposed to, you know,
either you are say, a tongue roller
or you are not a tongue roller. Either you have blue eyes
or you don’t have blue eyes. Like, knowing of course the blue eyed
example is completely false. So, some phenotypes are
yes or no. Pink–white flowers versus purple flowers
in our pea plants. That’s an example of something that’s really straight
forward and simple. But if we had this range,
kind of a bell curve example, then we would be more
likely to think, oh, I bet there’s multiple genes
that are contributing to this. Okay, the next one is awesome. I’ll be right back
to talk about pleiotropy.

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