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Posts posted by ecoli

  1. I like the subjectivism in English. It makes a nice change from silence. There's no definitive answer. There's no one intepretation. Every opinion is valid as long as you can back it up with fact. I enjoy using both styles of thinking

  2. Could anyone help me with this problem?



    a force of 40.0N accelerates a 5.0kg block at 6.0m/s^2 along a horizontal surface. How large is the frictional force? What is the coefficient of friction?


    I can't figure out how to get the force of friction without given the proportionality constant.

  3. Technically you're right, but it's my fault I should have made the picture clearer. By the question mark, I meant you didn't know the phenotype or genotype of the mother. I'm sorry, that doesn't make to much sense. How could you see the phenotype of one and not the other? I just creating a hypothetical situation. I should have been more specific. Sorry

  4. Dominant and recessive traits are not black and white. You have to keep in mind that a heterozygous dominant male can mate with homozygous recesive female. You won't know that the male is heterozygous until they have children. If any children express the recessive trait, then the male has to be heterozygous.




    In this picture a homozygous dominant male mates with homozygous recessive female. All there children are phenotypically dominant, although they are actually heterozygous dominant.




    In this picture a phenotypically dominant male mate with a recessive female. Becasue it expresses the dominant trait, there is no way to tell whether it is heterozygous or homozygous until it's children are born. Once you get a phenotypically recesive offspring, then the father has to be heterozygous, in order for it's children to recieve two recessive alleles.


    When creating a pedigree, its important to know what the children are in order to discover the genotype of the parent.




    In this picture the genotype of the mother is not known. But because on of the children is recessive (not shaded) and the father is phenotypically dominant, we know that the mother is hommozygous recesive, and the father is heterozygous dominant.

    The punent square would look like this:





    Or, both parents could be heterozygous Dominant, creating an offspring with recessive traits.





    The only way to know which situation is true, is to mate the recessive offspring and see what phenotypes occur in it's children.


    Creating a pedigree can be challenging, but interesting. Keep in mind, however that this form of punnet sqaure can only be used with looking at simple genes. Most phenotypes, in humans especially, are controlled by many genes. Its hard to create a genotype for a trait that is controlled by many different factors. Often times a dominant gene won't be expressed because of another gene controlling it.


    Hope I helped!

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