Genetics

• Gregor Mendel


  Father of Genetics
• Gregor Mendel


  • Biologist
  • Mathematician
  • Meteorologist
• Gregor Mendel was born


  July 20, 1822
• History of Gregor Mendel

  1. Lived in a monastery in Austria in 1842

  2. Moved to the University of Vienna where he studied science and mathematics in 1851

  3. Returned to monastery, taught, & kept a garden (most famous for studies on peas)
• Mendel's Pea Plant Experiment conducted between 1856 to 1863
• Genetics


  Study of heredity; how traits are passed from parents to offspring
• Heredity


  The passing of physical characteristics genetically from 1 person to another
• Inheritance


  Biological inheritance of traits controlled by genes
• Genes


  Basic unit of heredity passed from parent to offspring, made up of sequences of DNA arranged on chromosomes
• Children look similar to their parents because of the traits they inherit
• Gregor Mendel published many rules of heredity because of his observation
• Mendel's Initial Observation (Experiment)

  1. Crossed (mated) purple flowered peas plants with white flowered pea plants

  2. All the offspring had purple flowers

  3. Two of these first offspring were crossed, and some of their offspring had purple flowers, but a few had white flowers
• Characters


  Physical features that are inherited
• Trait


  One of several possible forms of a character
• Hybrid


  Offspring of a cross between parents with different traits
• Alleles


  Alternate versions of genes
• Alleles


  • For each character, there are 2 possible traits
  • Each trait is controlled by a specific gene
• Dominant Allele


  The allele whose trait is always expressed
• Recessive Allele


  Not expressed when a dominant allele is present
• We receive one allele for each character from each parent, so 2 alleles are needed to determine our traits
• Genotype


  All the alleles/genes inherited; an individual's genetic information
• Phenotype


  The physical expression of one's genotype
• Homozygous


  Genotype with 2 identical alleles
• Heterozygous


  Genotype with 2 different alleles
• Punnett Squares


  Model/tool that predicts the outcomes of a genetic cross
• Monohybrid Cross


  Cross between individuals involving one trait (just flower color)
• Incomplete Dominance


  An allele does not completely dominate another; phenotype will be a blend
• Codominance


  Both alleles for a trait are fully expressed
• Multiple Alleles


  A trait has 3 or more possible alleles
• Pea Plant Characters Mendel observed


  • Height of plant's stem (tall or short)
  • Position of flower on stem (mid-stem or end of stem)
  • Pod Color (green or yellow)
  • Pod Appearance (smooth or bumpy)
  • Seed Texture (round or wrinkled)
  • Seed Color (green or yellow)
  • Flower Color (purple or white)
• Petals give the flower a unique shape & have color to attract insects
• Nectary produces nectar (sugary substance that insects feed on
• Sepals are small parts growing at the base of the petals, look like tiny leaves
• Peduncle is the thickened part that holds the major flower organs
• Stamen is the male organ of the flower that contains 2 parts: Anther and Filament
• Anther is responsible for the production of pollen (which contains the male gamete)
• Filament is the stalk that holds & supports the anther and attaches it to the flower
• Pistil or Carpel is the ovule producing part of a flower (female reproductive) with 3 parts: Stigma, style and ovary
• Stigma is the sticky structure that pollen attaches to
• Style supports the stigma, connects the stigma to the ovary