Genetics

• Allele


  Alternate form of a gene, represented by letters
• Gene


  Segment of DNA on a chromosome that controls a certain trait
• Genotype


  Genetic makeup
• Phenotype


  Organism's appearance
• Uppercase and lowercase letters represent different alleles
• Bb x Bb - Punnett Square
• BB = Homozygous dominant
• Bb = Heterozygous dominant
• bb = Homozygous recessive
• Genotype Ratio: 1BB:2Bb:1bb
• Phenotype Ratio: 75% Brown Fur, 25% White Fur
• Genetics


  Field of biology devoted to understanding how characteristics are transmitted from parents to offspring
• Heredity


  Transmission of characteristics from parents to offspring
• Trait


  Category within which alternate characteristics, such as height and eye color, can be observed
• Pollination


  Transfer of pollen grains from the male anther of a flower to the female stigma
• Self Pollination


  Pollen is transferred from the anthers of a flower to the stigma of either the same flower or a flower on the same plant
• Cross Pollination


  Involves flowers of two separate plants
• Strain


  Plants that are pure for a specific trait
• Mendel's Experiment


  1. Grew pure strains

  2. Controlled pollination

  3. Observed traits in offspring
• P Generation


  Parental generation; plants that always produced a certain trait
• F1 Generation


  First filial generation; offspring of the P generation
• F2 Generation


  Second filial generation; offspring resulting from cross-breeding the F1 generation
• Dominant


  Visible form of a trait
• Recessive


  A gene that can be masked by a dominant gene
• Law of Segregation


  States that a pair of factors is segregated or separated during the formation of gametes
• Law of Independent Assortment

  States that factors for different characteristics are distributed to gametes independently
• Mendel's conclusion


  Paired factors separate during the formation of reproductive cells. Each reproductive cell, or gamete, receives only one factor of each pair.
• Law of segregation


  A pair of factors is segregated, or separated, during the formation of gametes.
• Mendel crossed plants that differed in two characteristics, such as flower color and seed color.
• The data from these more complex crosses showed that traits produced by dominant factors do not necessarily appear together.
• Law of independent assortment


  Factors separate independently of one another during the formation of gametes.
• Formation of reproductive cells


  1. Paired factors segregate

  2. Each gamete receives one factor of each pair
• Gametes combine during fertilization

  Offspring have two factors controlling a specific trait
• A green seed pod produced by a dominant factor could appear in a white-flowering pea plant.
• Another Punnett square yielded 2 black: 2 brown.
• Genotypic ratio


  Ratio of different genotypes in the offspring
• Phenotypic ratio


  Ratio of different phenotypes in the offspring