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Test Cross & Non-Mendelian Genetics. A Test Cross What if an organism has a dominant phenotype? Is it homozygous or heterozygous? Dominant.

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Presentation on theme: "Test Cross & Non-Mendelian Genetics. A Test Cross What if an organism has a dominant phenotype? Is it homozygous or heterozygous? Dominant."— Presentation transcript:

1 Test Cross & Non-Mendelian Genetics

2 A Test Cross What if an organism has a dominant phenotype? Is it homozygous or heterozygous? Dominant

3 A Test Cross Do a test cross. Breed it with itself or a true breeder (an organism you know is homozygous recessive). X PP or Pp pp

4 A Test Cross Look at what offspring are produced. Do to punnett squares PP x pp & Pp x pp X What are the possible offspring? PP or Pp ?

5 Dominant: ( P ) __Purple flowers_______ Recessive: ( p ) __white flowers_______ Parents: PP X pp Possible Sperm: ______ Possible Egg: ______ Offspring: Genotypes: __________________ Ratio: _______________________ Phenotypes: _________________ Ratio: _______________________ Test Cross #1 w/ recessive pure breed

6 Dominant: ( P ) __Purple flowers_______ Recessive: ( p ) __white flowers_______ Parents: Pp X pp Possible Sperm: ______ Possible Egg: ______ Offspring: Genotypes: __________________ Ratio: _______________________ Phenotypes: _________________ Ratio: _______________________ Test Cross #2 w/ recessive pure breed

7 Dominant: ( P ) __Purple flowers_______ Recessive: ( p ) __white flowers_______ Parents: Pp X Pp Possible Sperm: ______ Possible Egg: ______ Offspring: Genotypes: __________________ Ratio: _______________________ Phenotypes: _________________ Ratio: _______________________ Test Cross #3 w/ itself

8 Dominant: ( P ) __Purple flowers_______ Recessive: ( p ) __white flowers_______ Parents: PP X PP Possible Sperm: ______ Possible Egg: ______ Offspring: Genotypes: __________________ Ratio: _______________________ Phenotypes: _________________ Ratio: _______________________ Test Cross #4 w/ itself

9 Complex Inheritance Patterns Incomplete DominanceIncomplete Dominance –a blending of alleles RR = red flower RR = red flower WW = white flower WW = white flower RW = pink flower RW = pink flower CodominanceCodominance –both are expressed at the same time 100% each S bl – black fur S bl – black fur S br – white fur S br – white fur S bl S br – black and white spots S bl S br – black and white spots

10 Homozygous: ( ) ___________ Heterozygous: ( ) ___________ Homozygous: ( ) ___________ Parents: ______ X ______ Possible Sperm: ______ Possible Egg: ______ Offspring: Genotypes: __________________ Ratio: _______________________ Phenotypes: _________________ Ratio: _______________________ Incomplete Dominance

11 Homozygous: ( ) ___________ Heterozygous: ( ) ___________ Homozygous: ( ) ___________ Parents: ______ X ______ Possible Sperm: ______ Possible Egg: ______ Offspring: Genotypes: __________________ Ratio: _______________________ Phenotypes: _________________ Ratio: _______________________ Incomplete Dominance

12 Homozygous: ( ) ___________ Heterozygous: ( ) ___________ Homozygous: ( ) ___________ Parents: ______ X ______ Possible Sperm: ______ Possible Egg: ______ Offspring: Genotypes: __________________ Ratio: _______________________ Phenotypes: _________________ Ratio: _______________________ Co-Dominance

13 Homozygous: ( ) ___________ Heterozygous: ( ) ___________ Homozygous: ( ) ___________ Parents: ______ X ______ Possible Sperm: ______ Possible Egg: ______ Offspring: Genotypes: __________________ Ratio: _______________________ Phenotypes: _________________ Ratio: _______________________ Co-Dominance

14 Polygenic & Epistasis Polygenic TraitsPolygenic Traits = several genes affect one trait. e.g. skin color, height.

15 Skin color is a polygenic trait. The more recessive traits you have the lighter the skin. (aabbccdd) The more dominant traits you have the darker the skin. (AABBCCDD) What skin color does this person have (AaBbCcDd)?

16 AaBbCcDd x AABBCCDD = ______________ Probability of this offspring = ______________ Genotypes: ______ Ratio: ___________ Genotypes: ______ Ratio: ___________ Genotypes: ______ Ratio: ___________ Genotypes: ______ Ratio: ___________

17 Height is a polygenic trait. The more recessive traits you have the shorter you are. The more dominant traits you have the taller you are. Take a card and mate with someone. Determine the probability of the offspring on the card.


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