11.3 - Other Inheritance Patterns

• Law of Independent Assortment

  • Each gene/chromosome pair lines up along the equator for metaphase, independently of the next homologous pair. Alleles, therefore, could be sorted into gametes in different combinations. This random line-up causes a ton of variation in the gene combinations in gametes.
• Incomplete Dominance

  • The dominant form an allele is expressed (dominant) in the heterozygous state
  • 3rd phenotype is a blend of the two homozygous phenotypes
• Codminance

  • Both alleles for a trait are expressed (dominant)
  • 3rd phenotype will be a combination of the other two phenotypes shown at the same time
• Multiple Alleles

  • Genes that are controlled by more than two alleles are said to have multiple alleles
  • An individual still has two alleles for the trait - however, more than two possible alleles exist
  • This causes increased number of phenotypes because there are more allele choices
  • Ex: Blood types - Alleles: A, B, and O
• Polygenic Traits

  • Many traits are controlled by more than 1 gene 🡪 harder to predict and have many phenotypes
  • Height, weight, hair color, eye color in humans
  • Many of these are also affected by the environment like temperature, sunlight, and chemicals