SCIENCE 8

• Dominant


  An allele, gene or trait that is expressed, represented by a capital letter
• Recessive


  A gene whose effects are masked in the presence of a dominant gene, represented by a small letter
• Homozygous


  An organism that has the same two copies of a gene
• Heterozygous


  An organism that has different copies of a gene for a particular trait
• Genotype


  An organism's genetic information, the different copies of genes for a particular trait
• Phenotype


  The combination of an organism's observable characteristics or physical traits
• Gregor Johann Mendel was an Austrian biologist who developed the laws of inheritance
• Law of Dominance


  When an organism is heterozygous, only the dominant allele will produce a phenotype
• Law of Segregation


  Each individual has a pair of alleles for a particular trait
• Law of Independent Assortment


  Different genes and their alleles are inherited independently within sexually reproducing organisms
• Characteristics Mendel tested in his experiments

  • Round or wrinkled seed form
  • Yellow or green seed color
  • White or purple flower
  • Full or constricted pod form
  • Yellow or green pod color
  • Actual or terminal flower position
  • Long or short stem size
• Using a Punnett Square

  1. Write the genotypes of the parents

  2. Cross the genotypes to determine the possible offspring genotypes

  3. Determine the phenotypes of the offspring
• The offspring of a parental cross of pure breeding plants are called the F1 generation
• When the F1 generation plants are crossed with each other or self-pollinated, the offspring are called the F2 generation