Mendelian Genetics

• Allele

  A version or option for a particular gene
• Dominant

  • Traits that are more likely to pass to future generations
  • Only one dominant allele needed for the dominant trait to pass on
  • Dominant alleles are depicted by a capital letter
• Recessive

  • Traits that are less likely to pass to future generations
  • Both alleles must be recessive for the recessive trait to pass on
  • Recessive alleles are depicted by a lowercase letter
• Homozygous

  • Two of the same allele for a particular gene
  • Homozygous Dominant = 2 dominant alleles 
  • Homozygous Recessive = 2 recessive alleles
• Heterozygous

  • Two different alleles for a particular gene: one dominant, one recessive
  • Heterozygous traits show as  dominant traits
  • Always write the capital letter first
• Genotype

  • The alleles that one has for a specific gene 
  • A set of letters depict a genotype
• Phenotype


  The actual trait that appears as a result of the genotype