Non-Mendelian Genetics Inheritance patterns that are neither dominant nor recessive

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  • Non-Mendelian GeneticsInheritance patterns that are neither dominant nor recessive

  • Do Now: Take out homework. Thenclear desks.Homework: finish practice sheets

  • Genetics:Dihybrid CrossesBbHh X bbhh (parents)What gametes will each parent produce?What will be the genotypes of their offspring?What would be the phenotypes?

  • Easter Egg GeneticsPP=purplepp=pinkPp=orangeBB=bluebb=yellowBb=greenBp=redBP=whitePb=yellow spottedbp=white spottedBlack=genetic mutation!!!An egg may be all purple, so it was PP crossed with PP. Or it may be orange and pink, meaning it was Ppxpp.

  • In Mendelian genetics (Complete dominance), there are only two possible phenotypes: dominant or recessive

    Tall plant X Short plant = Tall plant (TT) (tt) (Tt)

  • But, not all inheritance is based on the rules of Complete Dominance!!

  • Other inheritance patterns include:Incomplete InheritanceCodominanceMultiple AllelesPolygenic TraitsSex-linked

  • 1. Incomplete Inheritance: Blending traitsNeither trait is dominantHybrids BLEND to make a medium phenotypeRed Flower X White Flower = Pink (RR) (WW) (RW)

  • Incomplete Inheritance ProblemWhat is the probability of pink flowers if pink flowers are bred with red flowers?

    50% chance of Pink Flowers

  • 2. CoDominance: Traits show up together as spots or stripes

    Co = together

    Black Cow X White Cow = Spotted Cow (BB) (WW) (BW)

  • CoDominance ProblemWhat are all the possible phenotypes when two spotted cows are bred?Possible phenotypes are a black cow, 2 spotted cows, and a white cow

  • Below are imaginary organisms. Note horn shape, leg length, fur color and tail shape. Now determine the type of inheritance of the four traits by examining the genotypes of the parents and offspring.

  • 3. Multiple Alleles: More than 2 types of alleles exist for a traitRabbits have more than 144 alleles for coat color!

  • The same allele can be dominant or recessive depending on context:agouti > black > albino

    What will offspring look like if a heterozygous agouti/black rabbit was crossed with an albino rabbit?

  • Blood type is determined by Multiple alleles and Co-dominancePeople have different blood types because of different carbohydrates on their surface.

  • Blood Type Inheritance Rules:A person with the IA allele will have A carbohydrates. A person with the IB allele will have B carbohydrates.A person with the recessive i allele will have no carbohydrates.Or a person with both IA and IB alleles will have both A and B carbohydrates on their cells.

  • Blood Type ProblemsIf a woman with AB blood has children with a man who has type O, what will be the possible genotypes of their children? What will be their blood types? IAIBiiIA iIA iIB iIB i

    CellsGenotypesBlood typesIAi, IAIAType A bloodIBi, IBIBType B bloodIAIBType AB bloodiiType O blood

  • Ever wonder why there are ranges of skin colors, or eye colors, or hair colors, or height?

  • 4. Polygenic Traits: Require the interpretation of many genes

  • Parents: Ll Mm Nn X Ll Mm NnThis also explains why a couple with heterozygous genes can have children who look so different.This child received mostly dominant genesThis child received mostly recessive genes

  • Why are some traits like color-blindness, ALD and hemophilia found mostly in boys?

  • 5. Sex-linked: genes are found on the sex chromosomes (X or Y)Most of these traits are recessive, the normal gene is dominant

  • Sex-linked inheritance rulesHeterozygous Females (XXc) are carriers. They do not show the trait, but carry a gene for the trait.Homozygous Females (XcXc) have the traitMales with the gene (XcY) have the trait.They do not have another X to counterbalance the affected gene

  • If a heterozgous woman with normal vision has children with a man who is colorblind, what are the chances that their children will be colorblind? Will any children be carriers of the trait?YXcYXYXcXcXXcXcYXY

  • Inheritance Summary

    Inheritance DescriptionPossible GenotypesPossible PhenotypesEx:Complete InheritanceOne trait is expressed when the allele is present, the other is expressed when both alleles are presentAA, Aa, aaDominant or recessivePurple or white flowersIncomplete InheritanceCodominanceMultiple AllelesPolygenic TraitsSex-Linked


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