Unit 3: Genetics Extras  Study Guide

Chapter 14 Mendel and the Gene Idea Review
  1. Gregor Mendel studied the of several characters with peas.
  2. Mendel proposed "heritable " (now known to be genes) to explain his results based on two principles of inheritance.
    1. Law of .
      • The allele determines a heterozygous individual's trait, or .
      • The phenotype ratio of the offspring can be calculated from a model called the square.
      • A testcross can be used to determine the of an organism with the dominant phenotype.
        Monohybrid Cross activity
    2. Law of Independent .
      • Crossing true-breeding parents differing in two traits produces in the F1 generation heterozygous for both traits, and phenotypes in the F2 generation.
        Dihybrid Cross activity
    Review: Mendelian genetics activity
  3. Extending Mendelian genetics.
    • In dominance, the phenotype of is somewhere between the phenotypes of homozygotes.
    • In , two dominant alleles affect the phenotype.
    • Some traits exhibit inheritance which often shows variation.
    • In , a gene at one locus may alter the phenotypic expression of a gene at a second locus.
  4. Inheritance in human families can be studied by analyzing a showing the inheritance of alleles across generations.
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