ANTH 110 1nd Edition Lecture 8 Outline of Last Lecture I. Simple InheritanceA. Mendelian Traits in Humans II. Polygenic Inheritance III. Mendel's Two Basic Laws of Inheritance (or Mendel's Postulates)Outline of Current Lecture I. Pleiotropy II. Variations on Standard Inheritance Patterns for Mendelian Traits A. CodominanceB. Incomplete DominanceC. Sex Linked TraitsD. Linked Traits III. PigmentCurrent LectureI. Pleiotropy Pleiotropy is when a gene has multiple affects. Whereas polygenic traits are a single trait that is affected by multiple genes, Pleiotropy is when one gene affects multiple traits. II. Variations on standard inheritance patterns for Mendelian traits A. Codominance Codominance is when a heterozygote has a unique phentotype. When the phenotype is codominant, both are at work as they generate a unique phenotype.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.The ABO blood group is an example of this. There are 4 phenotypes: A, B, O and AB. The allele for blood type A is dominant over O. The allele for blood type B is dominant over O. However, neither A nor B is more dominant. So, when an offspring receives both alleles, it will have AB blood type. The AB blood type is codominant. B. Incomplete Dominance Incomplete dominance is when a heterozygote exhibits an intermediate phenotype. In other words, it is in the middle between the dominant form and the recessive form. Hair is an example of this. Instead of having entirely brown or blonde hair, one can have a mix of both. C. Sex Linked Traits Sex linked traits for males are hemizygous. This means that they only receive one allele for a given trait. So, the trait will be expressed no matter what.Hemophilia, male pattern baldness, and some forms of color blindness are examples of this. D. Linked traits Linked Traits occur when you can inherit more than one feature directly from one of your two parents. This is when traits can be inherited as a package deal. If you get one, you will get the one that is linked to it. III. PigmentThere are two genes that deal with pigment, or melanin. One is Eumelanin (black/brown) and Phaeomelanin (yellow pigment). Example of how pigment works:Black labs can be: BBEE, BbEE, BBEe, BbEeYellow labs: BBee, Bbee, bbeeBrown lab: bbEE, bbEeHow does this work to generate the three different colors?The E gene is going to dictate whether B works or not. So, if one or more of the E alleles is dominant, then the B (black) will show. If the E alleles are both recessive, the B will not be activated and the dog will be yellow. If one or more E alleles are dominant, but the B alleles are recessive, then there is a mix of B and E that creates a brown dog. The point is that there is an interaction between the E and the
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