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Incomplete Dominance, Codominance, and Sex-Linked Pedigree chart

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Pedigree chart explains incomplete dominance, codominance, and sex-linked disorder.

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okay we have been looking exclusively at dominant versus recessive traits What Virgo Gregor Mendel knew to be true we look at his P plans we know that dominant eyes recessive  can I were going to look at types of inheritance that Mendel did not maybe true inheritance patterns that were discovered in organisms other than his classically study pea plants of the first one incomplete dominance  incomplete dominance is when two dominant alleles result in a blended phenotype so the key word here will be Blended  we're going to see a blended phenotype amongst offspring in a very common example would be flower color in snapdragons  a red Snapdragon has two copies of the filial  and a white dragon has two copies of the white allele  cancel their crossed they have offspring and that means that every Offspring inherits one red allele and one white allele we would describe the genotypes as being heterozygous because red and white are two different alleles just because they're both adamen doesn't mean how was I guess they're different dominant alleles red and white so you could say the parents are homozygous but the offspring would heterozygous  if I'm looking at phenotypes amongst Offspring You're told that this is an example of incomplete dominance and therefore we looking at a blending phenotype some when you blend red with white you end up with pink pink flowers so all of The Offspring between these two parents would be pink because we know that the gene for flower color and dragons is incompletely dominant to each other is that red and white being incompletely dominant to each other so if you Mayflower that inherits one of these red and white you are neither red nor white but the the intermediate or pink so the key here is a blending incomplete dominance as a blending of phenotypes in The Offspring being heterozygous if you're expressing the born to genotype you must be heterozygous two different alleles looking at another example and we're still speaking of dominant alleles here hot codominance is when to alleles result in both phenotypes the Express at the same time so what is different incomplete dominant and that you're going to see two distinctly different phenotypes Express at the same time so let's look at another example chicken with all black feathers is crossed with a chicken that has all white feather can the result would be baby chickens that have a an allele for black feathers and an allele for white feathers but because it is cold ominance  the chicken will have both black southern and white feathers at the same time and so the picture showing you an example of The Offspring here and we sometimes called chickens checkered checkered chickens black and white feathers at the same time if I had told you that this was incomplete dominance then you would have heard that the offspring would be great because black and white Blended make gray but you are told otherwise is an example of codominance so you know that The Offspring is expressing two different phenotypes at the same time like I pluck one of those black spiders maybe all black I can pluck a white one out if you all white so they have both phenotypes on the same organism okay notice tell recessive alleles involved in completely dominant or blending codominance two phenotypes at the same time but there's no recessive no recessive no recessive alleles involved in these two examples I want to look at sex linked traits sex linked traits are sometimes referred to as x-linked because we will be studying alleles located on the X chromosome  so everybody has at least one copy of the X chromosome females have two copies males have one  I will look at several traits that are located on the X chromosome but the most common examples would be hemophilia color blindness in humans remember that more talking about diseases like hemophilia that disease is a result of a mutation or a defective allele are not there to cause disease what is a version of this Gene is the mutated version the defective or damaged version so this is not is the normal allele or version of the gene is there to code for making a protein that causes your blood to clot the defective version doesn't make the blood clotting Factor so the mutated version in this example is recessive so in order to have hemophilia you have to have two copies of the recessive allele  stop a female Terrier females have two X chromosomes and recall that carriers will always be heroes I guess meaning mom has a dominant allele  and a recessive allele  samanas normal Pinot typically she has a dominant allele that beats out the recessive so mom makes normal blood clotting factor and does not hemophilia  men only have one X chromosome so whatever they're dealt is what they're stuck with they do not inherit a second act to potentially hide what's on the other so if we look at Mom her dumb and hide the expression of the recessive on her other ex so she does not have him Ophelia when unaffected man he has a dominant he did not have hemophilia the Y chromosome does not get anything X and Y are not homologous they do not chernin's so you will always leave the y blank and that's the biggest mistake that's made when doing sex linked Punnett squares why it's not there is no allele for blood clotting Factor on the Y chromosome totally different  so let's fill in the peten go out comes here most Offspring between these two people so the top looks at female Offspring these are girls Heritage F chromosomes you would describe as this female right here as homozygous dominant he has two dominant alleles Big H Big H she sign  a daughter that inherits the dominant one parents in this case of dad and the recessive from Mom this is a heterozygous female also known as a carrier and looking at male offspring inheriting an X and A Y there is a chance at this couple could have a son that's phenotypically formal  all right carry your hair because it's thought it would be a carrier she's normal  hey Nails giveaway inherit of the recessive allele from Mom so he is affected he will have hemophilia he does not what other acts to cancel out the recessive on his 1X okay hit this female here has a recessive allele on her ex but then on her direct from the chromosome she has a dominant so she's fine males don't have that Luxury Theater get it or they don't so this case this couple would have a son with hemophilia because Mom is a carrier so there are a lot of things I could ask about this potential cross I could ask what chances of this couples having a son with hemophilia in which case you would just look at the male offspring  so the 50% chance that this couple would have a son with hemophilia a one out of two in terms of just having a child with hemophilia you would say 25% chance  hey because I know daughter of these two people would have hemophilia barrier like right here but she would not have hemophilia  okay so there's a couple of questions that could be posed about Offspring amongst these two people there's no such thing as a mail carrier when we talk sex lines because men either have it or they don't whatever adult whatever's on the X chromosome is what they have so you cannot be heterozygous or homozygous really because you only have the One X males males always inherit a sex linked trait from their mothers because males males inherit the Y chromosome from their dad case of sex linked traits are passed from mother to son so we're talking about hemophilia or color blindness that's passing mother because the mail gets his Y chromosome from his dad so you see things like hemophilia and color blindness much more often in men because they only have one X females can be carriers and not express the trait so this email here Mom at the top She carries ileal but she doesn't express it painful sex linked Punnett Square again mixture you  I always leave the y blank that you have nothing there right so do you should get you through the put a square packet you should continue working on it trying to do the other examples there will be some that are going to combine codominance and Play Down codominance and sex linked to make sure you're reading carefully and you are keeping track of which Wheels in which on the X chromosomes

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Incomplete Dominance, Codominance, and Sex-Linked Pedigree chart

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