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Incomplete dominance-­‐ no one allele dominates the other allele •  the different forms are blended in heterozygotes •  Ex: Four O’ Clock flowers •  Red flowers •  White flowers •  Pink flowers Trait is flower color forms Red R White W Pink RW Red Four O’ Clock Flower X White Four O’ Clock Flower geno RR WW R R W W X X R R W RW RW W RW RW Analysis Geno RW 100% Pheno Pink 100% Pink Four O’ Clock flower X Pink Four O’ Clock flower geno RW RW R geno RR I RW II WW I raLo 1:2:1 R W X R W R RR RW W RW WW Analysis W pheno Red I Pink II White I raLo 1:2:1 Codominance-­‐ both phenotypes are expressed at the same Lme Ex: blood type coat hair in horses feathers in chickens Red horse geno RR R x White horse WW R W W X R R W RW RW W RW RW Analysis Geno RW 100% Pheno Roan 100% MulLple alleles-­‐ more than two alleles for a trait Ex: blood type A allele-­‐ A *A & B alleles are codominant B allele-­‐ B
*A & B alleles are completely dominant over O O allele-­‐ o allele Blood types and genotypes Type A-­‐ AA, Ao Type B-­‐ BB, Bo Type AB-­‐ AB Type O-­‐ oo Woman with Type AB blood marries a Man with Type AB blood. What are the possible blood types of their childern? Woman Type AB X Man Type AB geno AB A AB B A B Analysis A B A AA AB B AB BB X Geno AA I 25% AB II 50% BB I 25% Pheno Type A I 25% Type AB II 50% Type B I 25% Woman with Type O blood is married to a Man with Type AB blood have a child with type O blood, can this happen? Woman Type O
X Man Type AB oo o AB o A B Analysis X o o A Ao Ao B Bo Bo Geno Ao II 50% Bo II 50% Pheno Type A II 50% Type B II 50% Polygenic traits-­‐ a trait controlled by many genes Ex: height skin color Sex-­‐Linked Genes •  Genes located on the X chromosome. •  Colorblindness-­‐ inability to see color (XC normal, Xc blind) •  Hemophilia-­‐ failure of blood to clot (XH normal, Xhhemophilia) •  Duchenne Muscular Dystrophy-­‐ loss of skeletal muscles (XD normal, Xdmuscular dystrophy) 2. Sex chromosomes-­‐ chromosomes that determine sex •  Human female XX •  Human male XY •  Chance of having a daughter or a son Mother and Father XX XY X
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•  Chance of having a daughter or a son Mother and Father XX XY X
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•  Chance of having a daughter or a son Mother and Father XX XY X
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50% chance of a daughter 50% chance of a son 3. Autosomes-­‐ the other 44 chromosomes containing genes 4. Pedigree-­‐ chart that shows relaLonship within a family including traits. •  Circle-­‐ female Square-­‐ male •  Circle/Square shaded in, individual has trait •  Circle/Square parLally shaded, individual is carrier for trait Males are XY If they inherit one X chromosome carrying the recessive allele, they will have the sex link condiLon Females are XX They must inherit two X chromosomes carrying the recessive allele to have the sex link condiLon Example Woman carrier for marries a Man who has hemophilia hemophilia XHXh XhY XH
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Example Woman carrier for marries a Man who has hemophilia hemophilia XHXh XHY XH
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Example Woman carrier for marries a Man who has hemophilia hemophilia XHXh XhY XH
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Example Woman carrier for marries a Man who has hemophilia hemophilia XHXh XhY Xh
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Example Woman carrier for marries a Man who has hemophilia hemophilia XHXh XhY XH
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Example Woman carrier for marries a Man who has hemophilia hemophilia XHXh XhY XH
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X Chromosome InacLvaLon •  Females have two X chromosomes, one is turned off, it becomes a Barr body.