The Story of Mendel

• Genetics


  The science which deals with how genes control the biological characteristics
• Gregor Mendel


  The father of genetics
• Mendel published his study on heredity

  1866
• Mendel's study remained unrecognized for more than three decades
• Abbot

  Mendel became the Abbot of his monastery in 1867 and ran it as the administrator
• Blending Theory of Inheritance


  Prior belief that a progeny will have traits that are a smooth blend between the parents' characteristics
• Mendel's Experiments


  • Utilized a two-hectare garden in the monastery
  • Studied plant heredity, where knowledge is still lacking during his time
• Garden pea or Pisum sativum

  The subject of Mendel's study
• Garden pea or Pisum sativum

  • Grow fast and easy to cultivate
  • Have numerous distinguishable traits
• The seven characters Mendel focused on

  • Seed shape/wrinkling
  • Seed endosperm color
  • Flower color
  • Pod shape
  • Pod color
  • Flower location
  • Plant height
• Characters


  The heritable traits of an organism
• Traits


  The descriptions or variations in the characters
• Hybridization


  Mendel performed hybridization studies where he crossed true-breeding plants with contrasting traits
• P gen


  Parental generation
• F1 gen


  First filial generation
• F2 gen


  Second filial generation
• Mendel's Findings

  • Supported the 3:1 pattern of inheritance he observed in the F2 generations
  • The genes are the heritable factors in organisms
  • The alleles are the alternative versions of genes
  • Each allele is inherited from a parent
  • The dominant allele will mask the expression of recessive allele
• Dominant traits


  Traits that are expressed and favored over their alternatives
• Recessive traits


  Traits that only surface if the organism has no copy of the gene for the dominant trait
• Alleles


  Alternative expressions of traits
• Mendel's Laws

  • Law of dominance
  • Law of segregation
  • Law of independent assortment
• Mendel assessed his experiments based on 7 traits of peas
• If the P-generation is purely purple, there is no possibility for the offspring to be white
• The round seed shape is the recessive trait
• Most of the genes that Mendel observed in the peas had two alleles
• Recessive traits can resurface after many generations