Incomplete Dominance, Codominance, Polygenic Traits, and Epistasis!

Amoeba Sisters2 minutes read

Non-Mendelian traits like snapdragons, human height, and speckled chickens defy regular Mendelian rules by not following the dominant allele showing the dominant trait principle. Snapdragons exhibit incomplete dominance, where a red flower (RR) crossed with a white flower (rr) results in pink offspring (Rr) due to the incomplete expression of the dominant allele.

Insights

  • Non-Mendelian traits like snapdragons, human height, and speckled chickens showcase genetic inheritance patterns that deviate from simple dominant-recessive relationships, introducing complexities like incomplete dominance, codominance, and polygenic traits.
  • Epistasis, a genetic interaction where one gene's expression is influenced by another gene, exemplified by llamas with wool color controlled by an epistatic gene, highlights the intricate interplay between different genetic factors in determining observable traits.

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Recent questions

  • What is incomplete dominance?

    Incomplete dominance is a genetic phenomenon where neither allele is dominant, resulting in a blending of traits.

  • What is codominance?

    Codominance is a genetic scenario where both alleles are expressed equally.

  • What are polygenic traits?

    Polygenic traits are determined by multiple genes and environmental factors.

  • What is epistasis?

    Epistasis occurs when one gene's expression depends on another gene.

  • What are non-Mendelian traits?

    Non-Mendelian traits do not follow regular Mendelian inheritance patterns.

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Summary

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Non-Mendelian Traits: Defying Mendelian Rules

  • Non-Mendelian traits like snapdragons, human height, and speckled chickens defy regular Mendelian rules by not following the dominant allele showing the dominant trait principle.
  • Snapdragons exhibit incomplete dominance, where a red flower (RR) crossed with a white flower (rr) results in pink offspring (Rr) due to the incomplete expression of the dominant allele.
  • Codominance, seen in some chicken breeds, involves both alleles being expressed equally, creating speckled chickens (BW) with black and white feathers.
  • Height and skin color are polygenic traits, determined by multiple genes inherited from each parent, with environmental factors also playing a role.
  • Epistasis occurs when one gene's expression depends on another gene, as seen in llamas where a gene controls wool color expression, resulting in albino llamas if the epistatic gene is cc.
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