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Published byLilian Patrick Modified over 9 years ago
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Key Terms: › Hybrid – Heterozygous Organism – Ff › Purebred Homozygous Dominant - FF Homozygous Recessive – ff › P Generation – Refers to the parent generation › F 1 – First Generation (first set of offspring) › F 2 – Second Generation (second set of offspring
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Mendel, the father of genetics, completed over 100 experiments examining inheritance patters (traits) in pea plants Today, instead of repeating all of his experiments, we can use Punnett Squares to predict the traits the offspring will inherit
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Monohybrid Cross only studies on trait
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Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › P 1 : RR x rr R r R r
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Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › P 1 : RR x rr Rr R r R r
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Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › P 1 : RR x rr Rr R r R r
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Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › P 1 : RR x rr Rr R r R r
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Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › P 1 : RR x rr F 1 Genotype: › Homozygous Dominant = › Heterozygous = › Homozygous Recessive = F 1 Phenotype: › Round = › Wrinkled = Rr R r R r
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Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › P 1 : RR x rr F 1 Genotype: › Homozygous Dominant = 0% › Heterozygous = 4 Rr, 100% › Homozygous Recessive = 0% F 1 Phenotype: › Round = 4, 100% › Wrinkled = 0% Rr R r R r
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Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › F 1 : Rr x Rr r R R r
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Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › F 1 : Rr x Rr RR r R R r
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Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › F 1 : Rr x Rr RRRr r R R r
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Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › F 1 : Rr x Rr RRRr r R R r
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Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › F 1 : Rr x Rr F 2 Genotype: › Homozygous Dominant = › Heterozygous = › Homozygous Recessive = F 2 Phenotype: › Round = › Wrinkled = RRRr rr r R R r
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Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › F 1 : Rr x Rr F 2 Genotype: › Homozygous Dominant = 1 RR, 25% › Heterozygous = 2 Rr, 50% › Homozygous Recessive = 1 rr, 25% F 2 Phenotype: › Round = 3, 75% › Wrinkled = 1, 25% RRRr rr r R R r
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Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › ? x ?
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Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy
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Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy Y
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Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy YY
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Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy Y Y Y
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Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy Y Y Y y
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Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy YY Y Y Y y
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Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy YY Y Y Y y
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Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy YY Yy Y Y Y y
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Trait: Seed Color › Yellow – Dominant › Green – Recessive › YY x Yy Genotype: › Homozygous Dominant = › Heterozygous = › Homozygous Recessive = Phenotype: › Yellow = › Green = YY Yy Y Y Y y
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Trait: Seed Shape › Yellow – Dominant › Green – Recessive › YY x Yy Genotype: › Homozygous Dominant = 2 RR, 50% › Heterozygous = 2 Yy, 50% › Homozygous Recessive = 0% Phenotype: › Yellow = 4, 100% › Green = 0% YY Yy Y Y Y y
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Incomplete dominance or codominance is when 2 alleles are dominant or expresses Four O’Clock Japanese Flower › Red – Dominant › White – Dominant RR – Red WW – White RW – Pink
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Four O’Clock Japanese Flower › Red – Dominant › White – Dominant RR – Red WW – White RW – Pink › RR x WW Genotypes: R W R W
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Four O’Clock Japanese Flower › Red – Dominant › White – Dominant RR – Red WW – White RW – Pink › RR x WW Genotypes: RW R W R W
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Four O’Clock Japanese Flower › Red – Dominant › White – Dominant RR – Red WW – White RW – Pink › RR x WW Genotypes: › RW = Pink, 100% RW R W R W
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Color of Mice › White – Dominant › Black – Dominant WW – White BB – Black WB – Grey › BB x WB Genotypes: B W B B
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Color of Mice › White – Dominant › Black – Dominant WW – White BB – Black WB – Grey › BB x WB Genotypes: BW BB B W B B
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Color of Mice › White – Dominant › Black – Dominant WW – White BB – Black WB – Grey › BB x WB Genotypes: › BB = Black, 50% › WB = Grey, 50% BW BB B W B B
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Polygenic Traits are traits that are controlled by two or more different genes › Example: Eye Color Skin Color
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Multiple Alleles for one trait › Example: Blood Type Blood TypeGenotype AI A I A or I A i O BI B I B or I B i O ABIAIBIAIB OiOiOiOiO
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Blood Type › Cross: I A I A x I B I B Genotypes: IAIA IAIA IBIB IBIB
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Blood Type › Cross: I A I A x I B I B Genotypes: IAIBIAIB IAIBIAIB IAIBIAIB IAIBIAIB IAIA IAIA IBIB IBIB
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Blood Type › Cross: I A I A x I B I B Genotypes: › I A I B = AB, 100% IAIBIAIB IAIBIAIB IAIBIAIB IAIBIAIB IAIA IAIA IBIB IBIB
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Blood Type › Cross: I A i O x I B i O Genotypes: IAIA iOiO IBIB iOiO
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Blood Type › Cross: I A i O x I B i O Genotypes: IAIBIAIB IBiOIBiO IAiOIAiO iOiOiOiO IAIA iOiO IBIB iOiO
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Blood Type › Cross: I A i O x I B i O Genotypes: › I A I B = AB, 25% › I A i O = A, 25% › I B i O = B, 25% › i O i O = O, 25% IAIBIAIB IBiOIBiO IAiOIAiO iOiOiOiO IAIA iOiO IBIB iOiO
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Sex Linked Traits are traits coded by the alleles only on the sex chromosomes (X or Y) In fruit flies, eye color is determined by the alleles found on the X chromosome › Red Eyes – Dominant › White Eyes – Recessive X R – Dominant Allele X r – Recessive Allele Some sex linked traits in humans include color blindness (X C X C or X C Y) and hemophilia (X h X h or X h Y)
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GenotypeSex and Eye Color XRYXRYMale; Red Eyes XrYXrYMale; White Eyes X R Female; Red Eyes X R X r Female; Red Eyes X r Female; White Eyes
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Fruit Flies › Cross: X R Y x X r X r Genotypes: XRXR Y XrXr XrXr
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Fruit Flies › Cross: X R Y x X r X r Genotypes: XRXrXRXr XRXR Y XrXr XrXr
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Fruit Flies › Cross: X R Y x X r X r Genotypes: XRXrXRXr XrYXrY XRXR Y XrXr XrXr
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Fruit Flies › Cross: X R Y x X r X r Genotypes: XRXrXRXr XrYXrY XRXrXRXr XRXR Y XrXr XrXr
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Fruit Flies › Cross: X R Y x X r X r Genotypes: XRXrXRXr XrYXrY XRXrXRXr XrYXrY XRXR Y XrXr XrXr
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Fruit Flies › Cross: X R Y x X r X r Genotypes: › X R X r = Female; Red Eyes, 50% › X r Y = Male; White Eyes, 50% XRXrXRXr XrYXrY XRXrXRXr XrYXrY XRXR Y XrXr XrXr
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Dihybrid Crosses study 2 traits on a Punnett Square › This punnett square will have 16 boxes instead of 4
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Plant Height and Seed Shape › Tall = Dominant › Short = Recessive › Round = Dominant › Wrinkled = Recessive Cross a Tall Round x Short Wrinkled › All Possible combinations of alleles in gamete: TTRR x ttrr TR; TR; TR; TR & tr; tr; tr; tr
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TR tr
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TtRr TR tr Phenotye: 16 Tall and Round, 100%
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Plant Height and Seed Shape › Tall = Dominant › Short = Recessive › Round = Dominant › Wrinkled = Recessive Cross two heterozygous tall and round: › ? X ? › All Possible combinations of alleles in gamete: ?
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Plant Height and Seed Shape › Tall = Dominant › Short = Recessive › Round = Dominant › Wrinkled = Recessive Cross two heterozygous tall and round: › TtRr X TtRr › All Possible combinations of alleles in gamete: ?
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Plant Height and Seed Shape › Tall = Dominant › Short = Recessive › Round = Dominant › Wrinkled = Recessive Cross two heterozygous tall and round: › TtRr X TtRr › All Possible combinations of alleles in gamete: TR; Tr; tR; tr & TR; Tr; tR; tr
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TTRRTTRrTtRRTtRr TTRrTTrrTtRrTtrr TtRRTtRrttRRttRr TtRrTtrrttRrttrr TRTrtrtR TR Tr tR tr
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Phenotypes: › 9 Tall and Round – 56% › 3 Tall and Wrinkled – 19% › 3 Short and Round – 19% › 1 Short and Wrinkled – 6% When you cross 2 heterozygous organisms in a dihybrid cross, you will always have: › 9 of the same phenotype – Dominant/Dominant › 3 of the same phenotype – Dominant/Recessive › 3 of the same phenotype – Recessive/Dominant › 1 of the same phenotype – Recessive/Recessive › 9 : 3 : 3 : 1
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