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OTHER PATTERNS OF INHERITANCE

OTHER PATTERNS OF INHERITANCE. Alleles for different traits are distributed to sex cells (& offspring) independently of one another. Law of Independent Assortment. Sex-Linked Traits. Trait determined by a gene on a sex chromosome (usually X ). Examples: Colorblindness Hemophilia

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OTHER PATTERNS OF INHERITANCE

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  1. OTHER PATTERNS OF INHERITANCE

  2. Alleles for differenttraits are distributed to sex cells (& offspring) independently of one another. Law of Independent Assortment

  3. Sex-Linked Traits • Trait determined by a gene on a sex chromosome (usually X). • Examples: • Colorblindness • Hemophilia • Muscular Dystrophy

  4. Sex-Linked Traits: *Females must receive 2 affected X’s in order to express the trait. • Females with only 1 affected X are carriers. • Males that receive one X from mother expresses the trait.

  5. Xc Xc X Y Cross a colorblind mother with a father who has normal vision: Give the genotypic and phenotypic ratios. Key: XcXc = colorblind mother XY = normal vision father Cross: XcXc (x) XY Sex-Linked Punnett Square Practice Genotypic Ratio: Phenotypic Ratio: Answer on next slide…

  6. Xc X XcX XcX Y XcY XcY Sex-Linked Key: XX = female XY = male Cross: XcXc (x) XY Xc Genotypic Ratio: 2:4 XcX 2:4 XcY Phenotypic Ratio: 2:4 Carrier Female 2:4 Colorblind Male

  7. “Many genes” ; Many traits are controlled by more than one gene; have a variety of choices for expression. Ex: _hair color, eye color, skin tone___ Polygenic Traits

  8. Genes that have more than 2 alleles Ex: blood group. There are 3 possible alleles for this gene. Multiple Alleles i ii

  9. A A i i Cross a female who is Type AA with a male who is Type O (ii): Give the genotypic and phenotypic ratios. Key: AA = mother ii = father Cross: AA x ii Blood Type Punnett Square Practice Genotypic Ratio: Phenotypic Ratio: Answer on next slide…

  10. A i Ai Ai i Ai Ai Blood Type Key: AA = female ii = male Cross: XcXc (x) XY A Genotypic Ratio: 4:4 Ai Phenotypic Ratio: 4:4 Type A Blood

  11. Neither allele has “complete” dominance over the other; heterozygous phenotype is a blendof the 2 homozygous phenotypes Ex: snapdragons R = red W = white RW = pink Incomplete Dominance

  12. W W R R Cross a red (RR) snapdragon with a White (WW) snapdragon. Give the genotypic and phenotypic ratios. Key: R = red flower W = white flower Cross: RRx WW Incomplete Dominance Genotypic Ratio: Phenotypic Ratio: Answer on next slide…

  13. W R RW RW R RW RW Incomplete Dominance Key: R = red W = white Cross: RRx WW W Genotypic Ratio: 0RR: 4RW: 0WW Phenotypic Ratio: 0 Red: 4 Pink: 0 White

  14. Incomplete Dominance Practice: Cross a pink snapdragon with a red snapdragon. Give the expected phenotypic and genotypic ratios. Key: __________________ Cross: _________________ Genotypic Ratio: ________________________ Phenotypic Ratio: ________________________

  15. Incomplete Dominance Practice: Cross a pink snapdragon with a red snapdragon. Give the expected phenotypic and genotypic ratios. R R Key: R = red W = white RW = pink Cross: _RW x RR__ Genotypic Ratio: __2RR: 2RW: 0WW__ Phenotypic Ratio: __2 red: 2 pink: 0 white_ R RR RR W RW RW

  16. Codominance – Both alleles share dominance and are always expressed if present. Ex: In chickens B = black feathers W = white feathers BW = black AND white feathers Codominance X

  17. W W B B Cross a black (B) rooster with a white (W) chicken. Give the genotypic and phenotypic ratios. Key: B = black feathers W = white feathers Cross: BBx WW CODominance Genotypic Ratio: Phenotypic Ratio: Answer on next slide…

  18. W B BW BW B BW BW CODominance Key: B = black W = white Cross: BB x WW W Genotypic Ratio: 0BB: 4BW: 0WW Phenotypic Ratio: 0 black: 4 black and white: 0 white

  19. CODominance Practice: Cross two black and white feathered chickens. Give the expected phenotypic and genotypic ratios of the offspring. Key: __________________ Cross: _________________ Genotypic Ratio: ________________________ Phenotypic Ratio: ________________________

  20. CODominance Practice: Cross two black and white feathered chickens. Give the expected phenotypic and genotypic ratios of the offspring. B W Key: B = black W = white BW = black and white Cross: _BW x BW__ Genotypic Ratio: __1BB: 2BW: 1WW_ Phenotypic Ratio: _1 black: 2 black and white: 1 white_ B BB BW W BW WW

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