<p>Fulmer, 2009 BIO</p><p>GENETIC CROSSES</p><p>Differentiate: Genotype</p><p>Phenotype</p><p>Homozygous</p><p>Heterozygous</p><p>Explain why a phenotype might not always indicate a genotype.</p><p>Probability:</p><p>Probability = Number of times an event is EXPECTED to happen Number of times an event COULD happen</p><p>Mendel’s experiments: Dominant trait occurred 6,022 Recessive trait occurred 2,001 What is the probability that the dominant trait will occur? Expressed as a percentage: Expressed as a ratio:</p><p>What is the probability that the recessive trait will occur? Expressed as a percentage: Expressed as a ratio: Fulmer, 2009 BIO</p><p>PREDICTING RESULT OF MONOHYBRID CROSSES</p><p>Monohybrid cross is . . . </p><p>HOMOZYGOUS X HOMOZYGOUS</p><p>Trait: Flower Color Dominant- PP purple Recessive- pp white Phenotype: Genotype:</p><p>HOMOZYGOUS X HETEROZYGOUS</p><p>Trait: Coat Color Dominant- BB black Recessive- bb brown Phenotype: Genotype:</p><p>HETEROZYGOUS X HETEROZYGOUS</p><p>Trait: Plant Height Dominant- TT tall Recessive- tt short Phenotype: Genotype: Fulmer, 2009 BIO</p><p>TESTCROSS</p><p>Can determine the genotype of any individual whose phenotype expresses the dominant trait, but is unknown if individual is actually homozygous or heterozygous for a trait.</p><p>Trait: Pod shape Dominant: II -Inflated Recessive: ii -Constricted Phenotype: Genotype:</p><p>INCOMPLETE DOMINANCE</p><p>-Occurs when the phenotype of a heterozygote is intermediate between the phenotypes determined by the dominant and recessive traits.</p><p>Trait: Flower Color Dominant: RR -Red Recessive: rr -White Phenotype: Genotype:</p><p>CODOMINANCE</p><p>-Occurs when both alleles for a gene are expressed in a heterozygous offspring. Trait: Blood Types Fulmer, 2009 BIO</p><p>DIHYBRID CROSSES</p><p>-Cross in which two characteristics are tracked. Thus four alleles from each parent can combine. </p><p>HOMOZYGOUS X HOMOZYGOUS</p><p>Trait: Seed texture Dominant: RR – Round Recessive: rr- Wrinkled</p><p>Seed color Dominant: YY – Yellow Recessive: yy – Green Phenotype: Genotype: Fulmer, 2009 BIO</p><p>HETEROZYGOUS X HETEROZYGOUS</p><p>Trait: Seed texture Dominant: RR – Round Recessive: rr- Wrinkled</p><p>Seed color Dominant: YY – Yellow Recessive: yy – Green Phenotype: Genotype:</p>