Mendelian Genetics

• Law of Independent Assortment

  Gamete production probabilities of offspring
• Each copy can be passed to the next generation
• Complete Dominance: Dominant allele completely masks the recessive allele in a heterozygous condition
• Four-o'clock plant flower color, Snapdragon plant flower color

  • R- red
  • r- white
  • RR – red
  • Rr – pink (intermediate phenotype)
  • rr – white
• Chicken feather

  • BB – black
  • Bb – gray (intermediate phenotype)
  • bb – white
• Law of Dominance

  Dominant allele completely masks the recessive allele in a heterozygous condition
• Law of Segregation


  When any individual produces gametes (sex cells), the copies of a gene separate or segregate so that each gamete receives only one copy
• Incomplete or Partial Dominance: A cross that produces an offspring with intermediate phenotype
• A farmer bred two peas. The peas are heterozygote tall. Tall allele is dominant over the small allele. Give the genotypic and phenotypic ratio of the offspring and probabilities of each
• Types of Dominance

  • Complete Dominance
  • Incomplete or Partial Dominance
  • Codominance
• Eggplant or Brinjal

  • P- purple
  • p- white
  • PP – Purple
  • Pp – violet (intermediate phenotype)
  • pp – white
• MULTIPLE ALLELES


  When there are more than two possible alleles for a trait in a population
• PARTIAL DOMINANCE


  Similar to incomplete dominance, where one allele is not completely dominant over the other, but the phenotype is a mix of the two alleles
• If you have IA allele, your RBCs can add N-acetylglucosamine to H substance
• If you have IA and IB allele, your RBCs can add both to H substance
• COMPLETE DOMINANCE


  When a dominant allele completely masks the effect of a recessive allele
• A man with heterozygous alleles for blood type A married a woman with blood type AB. Determine the genotypic ratio and phenotypic ratio of their offspring, exhibiting both codominance and complete dominance
• BLOOD TYPE A can be IA IA or IAi
• BLOOD TYPE AB can be IA IB or IBIA, exhibiting both codominance and complete dominance
• CODOMINANCE


  When both alleles contribute to the phenotype in a way that both are visible in the offspring
• INCOMPLETE DOMINANCE


  When neither allele is completely dominant over the other, resulting in a blending of traits
• ABO Blood groups have A and B antigens
• BLOOD TYPE B can be IB IB or IBi
• BLOOD TYPE O is ii
• Blood Agglutination is the clumping of blood together due to antibodies vs antigens
• If you have IB allele, your RBCs can add Galactose to H substance
• A blood type O woman married a man with blood type AB. Determine the probability of having a child with blood type A. Determine the probability of having a child with heterozygous allele for blood type B