11.1 - Mendelian Genetics

Cards (7)

  • Genetics: the study of heredity - how traits get passed from one generation to the next
    • ex: eye color, blood type, skin color
  • Gregor Mendel - An Austrian monk (mid 1800's) who was a gardener. Pioneer in studying genetic inheritance which is a huge component in biology.
  • Mendel's Experiments
    • Key terms:
    • self-pollination: pollen (sperm) from a plant fertilize its own eggs. The resulting seeds are all identical to themselves.
    • same plant!
    • cross-pollination: pollen from one plant fertilizes the eggs of another plant
    • two plants
  • Mendel's Experiments
    • Mendel called:
    • P = original parent generation (your parents)
    • F1 = 1st generation offspring (you)
    • F1 offispring of parents with different traits are called hybrids
    • F2 = 2nd generation offpring (your kids)
    • When Mendel crossed plants, the F1 looked like only 1 parent, not a blend of the two traits!
  • Mendel's Conclusions:
    • Inheritance and Dominance
    • Inheritances is determined by "factors" called genes, which are small portions of DNA that code for proteins
    • The proteins then control how a trait is expressed
    • Each trait Mendel studied was controlled by two genes that come in contrasting forms
    • Ex: the gene for "plant height" comes in two forms - tall & short
    • the two forms of a gene are called alleles
  • Mendel's Conclusions:
    • Inheritance and Dominance
    • Principle of Dominance
    • Some alleles are dominant and some are recessive
    • An organism that has a dominant allele for a trait will always express the dominant form
    • An organism that has a recessive allele for a trait will only show the recessive form of the trait when the dominant allele is not present
    • A dominant allele can mask or hide a recessive allele - Mendel noticed that the recessive form seemed to disappear in the F1 generation and reappear in the F2 generation
  • Mendel's Conclusions:
    • Law of Segregation
    • The pair of genes for a trait separate from one another in meiosis.
    • When Mendel crossed his F1 plants, the recessive form of the trait showed up in the F2
    • Ex: a parent plant who is Tt can pass an T or t to the offspring via the egg
    • The result of this process is an F2 generation with new combinations of alleles