Other Patterns of Inheritance

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Other Patterns of Inheritance
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Learning Objectives

• Describe examples of exceptions to Mendels
  principles.
• Explain the relationship between genes and the
  environment.

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Incomplete Dominance

• Some alleles are neither dominant nor recessive.
• Incomplete dominance One allele is not
  completely dominant over another.

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Codominance

• The phenotypes for both alleles are clearly
  expressed.
• Examples chicken feather color, human protein
  controlling blood cholesterol levels

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Multiple Alleles

• Many genes exist in more than two forms.
• Examples human blood types, fur color in
  rabbits

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Polygenic Traits

• Many traits are produced by the interaction of
  several genes.
• Examples eye color in fruit flies, coat color
  in dogs
• Traits typically show a wide variety of
  phenotypes.

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Non-Mendelian Inheritance

• Maternal inheritance influences from DNA of
  maternal mitochondria and chloroplasts
• Genetic imprinting chemical modification of
  certain genes

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Genes and the Environment

• Environmental conditions can affect gene
  expression
• and influence genetically determined traits.
• The of an
  organism is only partly
• determined by its
  .

phenotype
genotype
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Student Worksheet Answers