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Pedigree chart of ID,CD, PT, and Epistasis by Amoeba Sisters

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Another great video by Amoeba sisters on pedigree chart explained.

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what do snapdragon human height and speckled chickens have in common they are easily identified as Nam Indian traits by non-mendelian we mean genetically they are rule Breakers they don't follow the regular having a dominant allele means the dominant trait will show remember in our Guinea Pig video having a dominant allele represented by a capital H meant that the guinea pig would have hair only if there was no dominant present a genotype of play would there be a hairless guinea pig Delian trait but we're going to cover now is when these traits are numb in DeLand and they don't follow basic rules so let's first start by snapdragons we confess that when we heard this word we thought they were some really amazing kind of creature what are amazing but they're flowers so I don't know that's not what we envisioned something in between pink it's called incomplete dominance in incomplete dominance the dominant allele is not completely expressed when recessive allele is around there isn't really a clear down that allele if you cross a red flower and we're going to write it here big are Big R and white flower little our little are you are going to get offspring that are big are little are but unlike a mendelian trait if this is incomplete dominance that are allele is not completely expressed when the little are is around so big are a little liar in this case is pink if you cross two pink hours Big R little r like shown in this Punnett Square here you can get offspring that are red white or pink  incomplete dominance different from codominance codominance like a co-worker that prefix Co it should make you think together they work together via that is entirely to represent the alleles there is a color in some types of take a look at this pain at Square if you cross a black chicken represent it here by Bebe and a white chicken represent it here by w All The Offspring here are bwbw chickens are both black and white their speckled sea both trade show up the essence of codominance and you know what's more awesome than a speckled chicken except for those silkie bantam chickens by the way do people use different formatting for incomplete dominance and codominance some people like to use different letters in tirely for incomplete dominance and some people don't people also prefer to do exponents with codominance and some people don't formatting aside when you're solving these Punnett squares since we find this really does vary from classroom to classroom the real concept is that an incomplete dominance one allele is not completely dominant over the other so you see this almost in between phenotype codominance both alleles are expressed if the application that matters here height is fascinating in our immediate family pinky is to weather in Virginia are mom is also taller than petunia so how does that happen there isn't just one height Gene there's a lot of genes that determine your height what I mean by that is that you don't just have a pair of alleles like big a big a that will code for your height it's more like someone having a genotype of big a big a big b little B big seagull see and maybe more genes to ultimately determine your height and you inherit one L for each of the hi genes from each parent all of these genes work together to determine your height your skin color is also determined by many genes just your height these are called polygenic traits poly means many so many genes coding for one trait is what polygenic means weight both height and skin color can be influenced by environmental factors as well nutrition growing up can affect your height just to spending a lot of time the sun can affect skin color however this doesn't change the genetics for the straight and finally one more thing that we want to talk about epistasis what is Asus is when one gene really depends on another Gene for it to even be expressed I mean it really depends on this other Gene so let's pick an animal like okay llama let's see this mama has a dominant big Belial which means it's wool will be black so big bee big bee or Big B little beet means that it will have black wool and let's say that if a llama has a pair of recessive alleles Little Bee little be then it will have brown wool what is there is another Gene that controls whether this pigment will even be expressed in the llama in the first place in this hypothetical example Obama could have this other Gene coded for by big c big c big c little see or little C little C and its genotype however what has the genotype little C little see it will not allow the other Gene for wool color to even be expressed since we have two genes here the gene for color Gene that controls whether the color is even expressed this calls for our favorite 16 square dihybrid cross if you notice in the sty hybrid cross I'm too heterozygote llamas any llama with big bee Big B and Big B little B will typically give a black llama and Little Beaver people typically give a brown llama in all cases unless they inherit a little C little see if the Llama has a little C little C and its genotype then the gene for wool color is not expressed and the Llama is albino this means that no pigment is expressed at all interesting there are many non mendelian traits we have another video on multiple alleles and sex-linked traits these are also non-mendelian when you have these rule-breakers one last thing keep in mind that when problem solving in genetics you do not want to just assume it's non-mendelian unless what provide information or clues in the problem that might be well that's it for the ameba sisters and remind you to stay curious

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Pedigree chart of ID,CD, PT, and Epistasis by Amoeba Sisters

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