Science

• Mendelian Inheritance


  Inheritance of traits determined by genes passed from parent to offspring
• Johann Gregor Mendel


  Father of Genetics
• Inheritance of traits is determined by the gene which is passed from parent to offspring
• Sample of traits


  • Skin color
  • Hair color
  • Personality
• A hereditary factor is inherited by an organism from each of its parents
• Sometimes, the inherited trait may not be observable yet
• Phenotype


  Observable traits
• Genotype


  Genetic makeup, expressed by letters (e.g. "Aa", "Bb")
• Homozygous


  Condition where alleles for a gene are identical
• Heterozygous


  Condition where alleles are not identical
• Dominant Allele


  Masks the presence of another type of Allele
• Recessive Allele


  Masked allele
• Law of Dominance


  • In a heterozygous individual, only one allele will be expressed (dominant) and the other one will be masked (recessive)
  • The dominant trait is always seen
• Law of Segregation


  • Two alleles of a gene separate during fertilization and these alleles will unite randomly
• Monohybrid Cross


  Crossing over the traits of an individual with contrasting traits
• Law of Independent Assortment


  • The inheritance of one allele pair is independent of that of the other
• Dihybrid Cross


  Crossing over two contrasting traits
• Punnet Square


  Devised by geneticist Reginald Punnet to organize the crossed genotypes
• Gregor Mendel


  Austrian Monk, Father of Genetics
• Gregor Mendel's birth

  July 20, 1822
• Genetics


  Branch of science that deals with the control of characteristics of plants and animals
• Gene


  Basic unit of heredity
• Heredity


  Transfer of characteristics from parents to offspring
• Gregor Mendel published his study on heredity

  1866
• Gregor Mendel's study remained unrecognized for more than 3 decades
• Gregor Mendel became the abbot/head of his monastery

  1867
• Gregor Mendel's experiments

  • Utilized a two-hectare garden
  • Studied plant heredity
  • Used pea plant/pisum sativum
• Characters


  The heritable traits of an organism
• Traits


  Descriptions or variations in the characters
• Blending theory of inheritance


  All good traits of parents will go to offspring in a smooth blend
• Hybridization


  Process of true-breeding studied by Mendel, crossing true-breeding through contrasting traits
• Filial generations


  First filial, Second filial
• Mendel supported the 3:1 pattern of inheritance
• Alleles


  Inherited from a parent, can be dominant or recessive
• Heredity


  Process by which half from mother and half from father
• Variations


  Differences that occur among the individuals in a population
• Discrete traits


  Qualitative traits that exhibit variations observed distinctively
• Quantitative traits


  Traits that can change continuously
• Polygenic characters


  Controlled by multiple genes, mostly exhibit continuous variation
• Pedigree


  Pictorial representation of the transmission of a trait in a family line