Complex patterns of inheritance 11.2

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Complex patterns of inheritance 11.2
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Incomplete Dominance

• Incomplete dominance is a form of intermediate
  inheritance in which one allele for a specific
  trait is not completely dominant over the other
  allele. This results in a combined phenotype.

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Codominance

• Codominance describes genes that each have equal
  effect in making the character they control
  appear in offspring.

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Multiple alleles

• Multiple alleles involve a gene that has three or
  more alleles that are associated with it. An
  example is the gene for blood groups, where
  alleles are neither dominant or recessive, but
  combine to produce a final phenotypic result.
• Types A, B, AB, or O

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Epistasis

• Epistasis is an interaction between two genes
  where one allele hides the effect of another
  allele. An example is
  coat color in
  labs.

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Sex determination

• Humans have 46 chromosomes, or 23 pairs of
  chromosomes. One set of chromosomes determine
  sex and are referred to as sex chromosomes. The
  other 22 are referred to as autosomes.

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Sex-linked traits

• Traits controlled by genes on the X chromosome
  are called sex-linked traits.
• Why are more males affected by sex linked traits
  than females?
• Examples color blindness, hemophilia

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Polygenic traits

• Some phenotypic traits arise from interactions of
  multiple pairs of genes polygenic traits.
• Skin color is an example

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Environmental influences

• Environmental factors can influence phenotypic
  expression sunlight, water, temperature are all
  examples.
• Temperature and
• color expression