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Incomplete dominance

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Incomplete dominance is a type of inheritance where neither allele for a trait is dominant. When hybridizing two purebred parents with different alleles, the offspring express a combined intermediate phenotype rather than one or the other parental phenotype. For example, when crossing a red flower with a white flower, the hybrid offspring are pink instead of red or white. A cross between red and blue flowers produces purple offspring rather than red or blue.

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INCOMPLETE DOMINANCE Presented To: Sir Khalid Hussain Presented by :09040606-031
Mendel’s Principles • Inheritance of biological characteristics is determined by individual units known as genes. • During sexual reproduction, genes are passed from parents to offspring. • Two or more forms of the gene for a single trait exist, some forms of the gene may be dominant and others may be recessive.
What is Incomplete Dominance?  Incomplete dominance is a type of inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a combined phenotype  (expressed physical trait).
Example……………….. • In Four O’ Clocks, if you cross a red RR (which is always pure) with a white WW (that is also always pure) , you get a pink RW (which is always hybrid /heterozygous)
Incomplete Dominance
Red Pink white
Incomplete Dominance • In incomplete dominance, neither allele is dominant so there is a blending of traits when two different alleles for the same trait occur together. • Colors blend together heterozygous individuals = 3rd phenotype
Incomplete Dominance • In another flower, if red RR and blue BB flowers are crossed, they produce a 3rd purple RB flower • What would be the genotype ratio and phenotype ratio if you crossed two purple flowers?
Incomplete Dominance • Cross of two purple flowers RB X RB R B • genotype ratio RR RB 1RR : 2RB : 1BB R red purple • phenotype ratio 1red : 2 purple : 1 blue B RB BB purple blue

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Incomplete dominance

  • 1. INCOMPLETE DOMINANCE Presented To: Sir Khalid Hussain Presented by :09040606-031
  • 2. Mendel’s Principles • Inheritance of biological characteristics is determined by individual units known as genes. • During sexual reproduction, genes are passed from parents to offspring. • Two or more forms of the gene for a single trait exist, some forms of the gene may be dominant and others may be recessive.
  • 3. What is Incomplete Dominance?  Incomplete dominance is a type of inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a combined phenotype  (expressed physical trait).
  • 4. Example……………….. • In Four O’ Clocks, if you cross a red RR (which is always pure) with a white WW (that is also always pure) , you get a pink RW (which is always hybrid /heterozygous)
  • 6. Red Pink white
  • 7. Incomplete Dominance • In incomplete dominance, neither allele is dominant so there is a blending of traits when two different alleles for the same trait occur together. • Colors blend together heterozygous individuals = 3rd phenotype
  • 8. Incomplete Dominance • In another flower, if red RR and blue BB flowers are crossed, they produce a 3rd purple RB flower • What would be the genotype ratio and phenotype ratio if you crossed two purple flowers?
  • 9. Incomplete Dominance • Cross of two purple flowers RB X RB R B • genotype ratio RR RB 1RR : 2RB : 1BB R red purple • phenotype ratio 1red : 2 purple : 1 blue B RB BB purple blue